OneFiercePuppy: Well, for turn-based, squad tactics games, there are only two you really need to play, because both of them are perfect: X-Com, and
Jagged Alliance 2. Since you've already mentioned the first, I'd say try the other ^_^
I'm not a good judge of RTS, so I'm no help there, sadly.
I will try Jagged.
tinyE: Robin Hood Legend of Sherwood (same developers as Desperados)
Crookz
I already played it is a really good game.
drealmer7: squad-based TB:
Fallout: Tactics and Wasteland 2
I had to play Wasteland!
P1na: If you're looking carbon copies, Robin hood: legend of sherwood is a reasonably safe bet.
Still, commandos was more of a puzzle game than a strategy/tactics game. If you head more to the tactic side of things, depending on the take you want, W40k: Dawn of war 2, fallout tactics and Satellite reign might do the trick. The UFO series follows the X-com formula somewhat and is real time with pause.
I tried UFO but is a bit weird, and W40k i never play that thing.
hyperagathon: Another game in a similar vein to Commandos / Desperados is Robin Hood: The Legend of Sherwood.
There's a game similar to X-COM popping up at every corner recently. But since you specifically compare those two, perhaps Xenonauts will prove more satisfying? Depending on what you're looking for in such a game, I can think of Hard West, Chroma Squad and Telepath Tactics as some recentish examples.
Syndicate / Syndicate Wars....how about the "spiritual successor", Satellite Reign?
Xenonauts seems good, Satellite Reign didn't work in my PC sadly.
Hard West feels amazing!
Thank you all, i will try Hard West.