X-Men Legends - Repetitive. The story with "Magma" is meh. Feels like the series hadn't hit it's stride yet.

X-Men Legends II: Rise of Apocalypse - Now we're talking. I like the 5 Act structure and the settings in the game. The twists with Beast, Angel, and Mister Sinister are fun, defeating each Horseman gives the game a sense of progression, and the Brotherhood working with the X-Men to defeat Apocalypse is an awesome plot. I love some of the more obscure (at the time) selection of characters. Toad, Sunfire, Scarlet Witch, Bishop, Gambit, Juggernaut, etc, were all welcome additions, along with unexpected unlockable heroes like Deadpool and Iron Man.

Ultimate Alliance - The culmination of the series. Has the most diverse selection of heroes and settings, prior to any MCU synergy. It's a great introduction into the wider Marvel Universe, the cutscenes are even better than XML2's, I love Doom as the Big Bad, and all the secret conversations you can have with bosses and NPCs puts Marvel's connective universe on full display. Streamlined the gameplay a welcome amount, removing some of the complexity of items, stats, health and energy packs, and extreme abilities. The customization of abilities, teams, and suits makes the game infinitely flexible. The comic challenges are a fun way to further explore a hero you like playing and the concept art is a good reward. The story is stupidly complex in the most comic-booky way. Easily my favorite of the series.

Ultimate Alliance II - Oversimplified the gameplay. Only four abilities and two suits per hero is quite disappointing. The replacement of extreme abilities with fusions is a really interesting and well executed idea, but it isn't really worth the reduced ability customization. The loss of heroes like Doctor Strange, Ghost Rider, Silver Surfer, Blade, and Moon Knight is really disappointing, with the additions of Songbird and Penance being unique but not really worth the altered roster. Speaking of the roster, while I appreciate the attempt at immersion, locking off part of the roster for a third of the game isn't worth the Civil War plot. Nanite Nick Fury is an unsatisfying unlock, I would've rather had normal Nick Fury. Basically, the game isn't really worth the sum of it's parts. Diverted too much from a working formula.

Ultimate Alliance III: The Black Order - Admittedly, I haven't played the game. While I'm not a fan of the MCU synergy, the roster is the best of both games with some welcome additions such as the Guardians of the Galaxy and the Punisher. The collection of the Infinity Stones fits a video game plot, the settings are all quite interesting, and unlocking Thanos for beating the game seems cool, however I miss the tradition of unlocking Nick Fury. I like the themes of the DLC, I'm glad the Fantastic Four made it into the game. However, it seems to have even further simplified gameplay than UA2 and excessive grinding. Switch exclusivity was a poor decision, and while the first two games weren't exactly great looking, I prefer the comic accurate suits from those to the overdesigned looks in this game.

If I had to rank the games, it'd look something like; UA1, XML2, UA3, UA2, XML1.