Which Prince of Persia game on Steam is the best?

Okay.

Prince of Persia: Sands of Time - Great game, equal mix of platforming, puzzle and combat (maybe little bit more combat than you would expected), It's game for 'kids'

Prince of Persia: Warrior Within - Well, I guess this one was okay, but I didn't like it much. I had to keep pushing myself to finish it, however when you do that and you get yourself more into the story, you gotta play it in one night :D Also if you wanna have the good ending, you gotta collect all the life upgrades, which sucks! It's game for 'adult'.

Prince of Persia: Two Thrones - I think this is my most favorite part, mainly because of the two versions of prince, he can transform to his 'dark' half, but it's scripted. You can't say like: "Transform you nigga!", the game's gonna do it, when prince needs it. It's mix of Warrior Within and Sands of Time, but I think it's like 70% for kids and rest for the adults. It's my personal thoughts, so...

Prince of Persia 2008 - I liked it a lot, maybe second or third best PoP. But again, I had to push myself to collect that god damn sperms or whatever was that!

Prince of Persia: Forgotten Sands - Don't even bother with this shit.

I've only played some of Sands of Time so far, but that really impressed me. The platforming was good, the art style was gorgeous, and the storytelling was well done (even little touches like the Prince saying "Wait, wait, wait... that's not how it happened..." when the player died were great). I'd definitely recommend that one. Just be aware that it sometimes has a problem with multi-core CPUs. Just disable all but one core in Task Manager if you suffer any side effects like slowdown.

Original trilogy.