As some of you can remember, 3 years ago first two factions were added: Hall of Guardians and All-Seeing Eye. What did we see during this time?
First factions were not ideal, as retrospection shows. All-Seeing Eye remains the only one faction with 8 rooms, not 9. We like it, of course, for a useful weapon (Jar of Eyes) and for troops (Xerodar and Ocularen Leech at least), but it could be updated. Maybe something will happen with it soon? Hall of Guardians is better, but not very rich: no Legendary rooms at all. It has good weapon too (Guardian Crown) and useful troops (Gargoyle and Silent Sentinel).
As more factions were being added, a natural question appeared: which faction was better for everyday delves (3 delve scrolls granted to each player daily)? People held favorite factions at fixed level, i.e. did not passed the final Mythic room to prevent leveling, and collected as much resources as possible. There were no “Level 50” option with starting treasure multiplier 0.5 at those times, only previous level or current (with starting TM = 1), so for fully developed factions they were “490 with TM = 0.5 and 500 with TM = 1” only.
With City of Thieves coming into the game (30th August '19) it took the first place for user-friendliness. It had 3 treasure rooms, 2 Epics (occasional treasures) and 2 Legendaries, and you can pass them in any order you want - what could be better? This is a good example of looking for an optimal order, so a recipe was worked out quickly: increase treasure multiplier and then collect treasures. Mostly gold, sometimes glory and traitstones. Also, some gold, chaos shards, Legendary and Mythic ingots could come in rewards for a passed delve.
In February '20 the first option for delving was changed at last: you could pass level 50 with TM = 0.5 regardless of how far you’ve got in that faction leveling (but higher than 50, of course). So you could make this level 50 with Mythic room and collecting full rewards without changing actual faction level.
With factions regularly added to the game, total renown was raising with more different bonuses given to players: some daily gold (in addition to that from kingdoms), some ingots (Common mostly, but others being possible), stats increased. Some people did not want to wait for Tuesday Faction Assault event and tried to pass level 500 factions with pure teams to make renown 2500. It’s not difficult to make level 500 in any faction with a color restricted team and make renown 2000, but some factions’ pure teams are weaker than others. Some most easy factions are The Deep Hive, Emperinazar and Depths of Sin, while the most hard one are Fang Moor and The Labyrinth (see @TimeKnight 's list here: Delve's Statistic ).
With more and more factions coming is became easy to save delve scrolls in factions to pass them later, not strictly in the same day. But only 1 delve per faction only. So with 32 factions you can save delve scrolls for 10 days in a row, and then start to pass delves. And if you want to save scrolls wisely, you’ll need to choose factions with better possible outcome. City of Thieves - yes, that’s one, what are others? I tried to clarify it here: Everyday delves and backing them up .
Since June '21 factions broke their cycle and switched to the “follow your kingdom” principle (you can see that cycle here: Weeky Faction Assaults schedule - obsolete (created in June '20, updated 22 May '21) ). Following the kingdom was not always possible previously, because not all kingdoms had factions. Right now we just can tell that Blackhawk and Broken Spire won’t come as weekly kingdoms soon, just because they do not have connected factions yet.
What we can tell about specific factions? Are they good for mining resources, or for passing within a campaign, or for their troops and weapons, or just for fun?
All-Seeing Eye - useful troops Xerodar and Ocularen Leech and useful weapon Jar of Eyes, the worst faction for delves for resources and not the best one for a quick pass (3 rooms long though with an Epic room in the middle);
Amanithrax - a useful King Gobtruffle troop, not very good for resources and bad for a quick pass (5 rooms long), one of the easiest to pass with a pure faction team;
City of Thieves - one of the best factions for resources (both from rooms and from the final chest), not the best for a quick pass (3 rooms long, a Legendary room in the middle);
Crypt Keepers - useful Grave Seer and Lady Morana troops, useful weapon Secrets of the Crypt, not very good for resources, not the best one for a quick pass (3 rooms long with an Epic room in the middle);
Dark Court - a useful Leanansidhe troop, otherwise nothing special (4 rooms long), one of the easiest to pass with a pure faction team;
Dark Pits - a useful Sledgepaw troop, not the best for a quick pass (3 rooms long with a Legendary room in the middle);
Depths of Sin - somewhat useful for mining resources, not the best for a quick pass (3 rooms long with an Epic room in the middle), one of the easiest factions to pass with a pure faction team;
Dripping Caverns - specific troops and weapon, which can be used in Guild Wars defenses, somewhat useful for mining resources (the final chest mainly), not good for a quick pass (4 rooms long);
Duergaroth - good for mining resources (4 treasure rooms!), may be some fun to play with stone blocks: create or explode them, - not the best for a quick pass (3 rooms long with an Epic room in the middle);
Eldrazhor - useful Matron Velenne and Deep Huntsman troops, otherwise nothing special, not the best for a quick pass (3 rooms long with a Legendary room in the middle);
Emperinazar - A useful troop Emperinazara (thanks to @Sytro for pointing out), otherwise nothing specia (4 rooms long pass);
Fang Moor - a useful Chief Dargon troop, somewhat good for mining resources, not suited for quick passes (5 rooms long) and one of the hardest to pass with a pure faction team;
Fell Roost - somewhat good for mining resources, not good for quick passes (4 rooms long);
Frostfire Keep - can be good for mining resources, not good for quick passes (4 rooms long), one of the hardest to pass with a pure faction team;
Hall of Guardians - useful Gargoyle and Silent Sentinel troops, useful Guardian Crown weapon, not the best for a quick pass (3 rooms long with an Epic room in the middle);
Hell Gate - just an average faction, but troops and weapon may be useful for mining souls, not good for quick passes (4 rooms long);
Illithia - the best faction for quick passes: 3 rooms long with just a Rare room in the middle, moreover, you can choose between all 7 rooms to make a quick pass, otherwise not a very special faction;
Indrajit’s Palace - the most “chaotic” faction, so to say, with 6 rooms unpredictable from Rare to Legendary, may be some fun to hunt for top combinations there (6 Legendary rooms, for instance), not good for quick passes (4 rooms long);
Lyrasza’s Lair - a useful Lyrasza troop, somewhat good for mining resources, not good for quick passes (4 rooms long, but with many variants of middle rooms passage);
Mirrored Halls - curious troops Doppelganger and Copycat, good for mining resources (4 treasure rooms!), not the best for a quick pass (3 rooms long with an Epic room in the middle);
Primal Rift - a useful Alderfather troop, weapon somewhy connected to the Primal kingdom of imps, otherwise nothing special, not good for quick passes (4 rooms long);
Sea of Sorrow - somewhat useful the Deep King troop and good weapon Writhing Staff, otherwise nothing special, not good for quick passes (4 rooms long);
Silver Necropolis - somewhat useful Vanya Soulmourn troop and one of the best weapons Life and Death, not bad for mining resources, not the best for a quick pass (3 rooms long with an Epic room in the middle);
Stonesong Eyrie - useful Harpy Mage and Queen Xochi troops, otherwise one of poor factions, not the best for a quick pass (3-4 rooms long with 5 paths to choose between);
Sunken Fleet - a leader for useful troops: the Maraji Queen, Water Elemental and Drowned Sailor come from here, also a faction with a curious design: two Ocean rooms in the main path and one Naga room, - not bad for mining resources, not good for quick passes (4 rooms long);
The Deep Hive - a useful troop Queen Beetrix, otherwise an average faction, not good for quick passes (4 rooms long), one of easiest to pass with a pure faction team;
The Labyrinth - an average faction, but one of the hardest to pass with a pure faction team, not good for quick passes (4 rooms long);
The Warrens - useful Luna and Trickster troops and useful weapon Garland Staff, otherwise nothing special about it, definitely not good for quick passes (5 rooms long);
Tinker Town - useful Tink Steamwhistle troop, somewhat good for mining resources (3 treasure rooms), not good for quick passes (4 rooms long);
Werewoods - useful Beastmaster Torbern troop, otherwise nothing special, not good for quick passes (5 rooms long);
Wild Court - somewhat good for mining resources (3 treasure rooms), not good for quick passes (4 rooms long);
Wyrmrun - the best faction for mining resources (6 treasure rooms!), not good for quick passes (5 rooms long).
All delves’ plans can be found here: Delves: all about rooms and plans .
What we have in summary? About 27 troops of 128 from delves are useful not in delves only, and 7 weapon nice to have in your inventory. 6 factions are rather rich (3 or more treasure rooms), some are fun (like Indrajit’s Palace, or Illithia, or Eldrazhor).
Problems of delves were revealed here: On the Matter of Delves , they concern difficulty of getting renown 2500. Too much time, too boring - yes, that’s all applicable to delves.
Things can get a bit easier if you craft Zuul’Goth - it helps a lot in passing most delves. Another useful troop for delves is High King Irongut. If you do not have any of them, leveling factions can be really long.
What about 2 remaining factions? We do not have even spoilers for them now. Can we expect anything special? After dealing with stone blocks with Duergaroth troops, or playing against Indrajit’s Palace’s chaos, or farming resources in having come too late Wyrmrun - what then? And what will be after factions?..
