AD&D definitely has the slower/lower combat progression than the others. 5E has the same progression regardless of class. DCC and 3.5 mirror each other up until reaching 8th level except where the Fighter is concerned and DCC is using a die, instead of a static modifier. C&C has a similar progression as 3.5 and DCC until 3rd level and then slows progression, except Fighter. It's also interesting to see that in 3.5 and DCC, Cleric and Thief both have the same progression modifiers, where as C&C gives Thieves a slower progression than the Cleric. The Trolls need to give the Thief a face lift, it's lagging behind even compared to the AD&D thief.
Personally, I like the steadier progression in 3.5, but the combative power of the Magic-User and Thief compared to AD&D is a pretty big upscale. I also think the Cleric and Thief should have similar progressions, allowing the Fighters to have the highest/fastest and Magic-User the slowest, it just makes sense to me. 5E is just flat out boring and doesn't make any sense. Why all of the classes have the same progression, idk, but it seems like a terrible way to design the game.
