Here is a rundown:
Gold Chests - These contain a mixture of Common rarity troops (in white), Rare troops (in green), minor traitstones, major traitstones, and rarely either 400ish gold, 20 souls, or 1-2 gems.
Glory Chests - These contain all troops except Commons, all traitstones except minor, and rarely some gold, souls, or gems. The vast majority are going to be Rare and UltraRare (in blue). Mythics (in silver) occur around 1 in 10000 chests.
Gem Chest - These are like Glory Chests except no Common or Rare troops and no Minor or Major traitstones. UltraRare are the majority with some Epic (in purple). Mythics occur around 1 in 1000 chests
Event Chest - These are just like Gem Chest except any Lgendary (in orange) and Epic is from the Kingdom of the week. The UltraRares are typically from the Kingdom of the week, but rarely may be one of a few other UltraRares. It is assumed that if the Kingdom has a base Mythic, than it has a 1 in 1000 drop chance.
VIP Chest - These require VIP 5 to purchase. They give just Epic, Legendary, and Mythic troops. Mythic occur at a 1 in 100 chance. Epics and traitstones are given in pairs per chest. Additionally every chest gives 2000 gold.
Guild Chests depend on the level unlocked by your guild this week. At the lowest they are equal to a Gold Key. At level 6 they are Gem Keys. Regardless of guild progress though, every chest has a 50% of producing one of the guild guardians instead until you have all 6 at Mythic and have 4 of each.
In addition to all that, troops aren’t normally available from chests until 4 weeks after release. I do my best to maintain that list here - Updated "Not in chests" list