Not necessarily fully ascended, but definitely fully traited.
Example: Dwarven Gate might be ok in first spot without 50% skull reduction, depending if it can cast and barrier allies, but it might not be as good as a Dragonguard class if the Hero starts with barrier.
Off-topic, I’d suggest getting that Soul Forge unlocked so that your quest kills will help unlock the SF levels. (QoL improvement request: Have Forge auto-level)
On topic: My favorites are…
Common: Orc (used on Defense team with Drake Rider and Gar’Nok)
Rare: Tigraki Warrior (best Bounty Troop imo)
UR: Drake Rider for Delves/Defense; Goblin Rocket for PvP
Epic: Igneus/Faunessa for Delves
Legendary: Yao Guai for PvP; Alderfather/The Maraji Queen for Delves
Mythic: Infernus hurts my eyes too much…I prefer AW
Class: Thief (I traited Bandit and SoS with Stealthy…I’m an Orc; not a Troll)
Weapon: Mang for Delves; Doom of the Day for Defense
Pet: Puddling