Evaluating archers.

The strongest is the Titan.
The most useful is often the Gremlin, because at the beginning of the game, that ugly creature of the first level is quite effective... or the Cyclops, especially when they destroy your catapult with magic, and you don't have "Earthquake"...

Well, regarding usefulness - in my opinion, it's definitely the Elves - especially at the very beginning of the game, but they have a greater effect than that crowd of ugly creatures. And about the Cyclops - there are many other ways to get into a castle, so why should we love them just for that? - and what about their face? :D

The most correct question is in the second post: what criteria should we use to evaluate them?

I think everyone has already answered this question - everyone has their own opinion, saying "I think so, and the rest don't matter"... After all, agree - there were no clear rules, and everyone is arguing...