But that's the inferior one between the two... I liked the game, but nowhere near as much as the first. Then again, I was playing on the PS2, so I don't know, maybe that's why it wasn't as good for me.
The RPG elements were all but stripped out of UA2. UA1 took a small step in that direction by removing the random loot system found in XMen Legends 2, but UA2 went whole-hog and the experience into more of a basic brawler with Marvel fan service.
If you have any affinity for action-RPG's, then XMen Legends 2 is a must-play title:
every character has a sizable skill tree
the game has a relatively deep loot system with random drops and rarity levels
the combat system takes a lot from fighting games (combos, juggles, knock-downs, etc.)
the environments are skinned with highly destructible layers, and everything has an underlying HP system (eg. Cyclops' vanilla Optic Blast takes a few shots to bust a wall, but after popping a few skills points into it, one blast will shatter the wall)
there's lots of characters to choose from for your 4-person party, and you can swap them out on a frequent basis
there's a "new game+" mode so you can play with min-maxing
Game is still great on PS2, XBox, and PC; but stay away from the PSP version due to visual and loading issues.
In terms of playing UA1 again--which, BTW, is still a fun ARPG--your best bet is the XBox 360 (and PC?), as the PS3 version is a rough port with lots of framerate and resolution downgrades. I believe UA1 is also headed to XBone BC, if it isn't already.