Feel free to suggest other games, too. So far, I'm looking at

Crash: Nitro Kart
Sonic Riders
Lego Star Wars
The Incredibles
Star Wars: Bounty Hunter
Ty the Tasmanian Tiger
Shrek Superslam
Crash Bandicoot: The Wrath of Cortex
Sonic Adventure 2 Battle
Shadow the Hedgehog
Pac Man World 2
Spider-man: The Movie
Digimon World 4
Crash Tag Team Racing
Cars
Batman Begins
Spider-man: The Movie 2
Donkey Kong Jungle Beat
Super Mario Sunshine
Metal Gear Solid: the Twin Snakes
Tom Clancy's Splinter Cell
Tony Hawk's Underground 2
LoZ Ocarina of Time

They're both really bad, but XD improved on a lot of things.

I don't know--they're just boring and repetitive as fuck.

I hope you like constant double battles and tedious dungeon crawling, because that's all you do.

Anyway,

The Metroid Prime series is worth a try. I wasn't particularly into either of them, but they're rather popular.
Paper Mario: The Thousand-Year Door is one of the best Mario titles of all time.
Pikmin is... something different. Bizarre franchise. Hit or miss.
SoulCalibur II is a solid, content-packed fighting game--and on GameCube, you get access to Link from LoZ.
I would suggest Animal Crossing, but only if you have others to play it with.

There's also, like, five hundred thousand Mario Party titles to choose from.
Mario Kart: Double Dash!! is probably the least shit Mario Kart game, barring DS.

Wario World and Amazing Island are both dumbass games that are kinda niche, but I found them fun as a kid.

Don't bother with Twilight Princess, since its coming out in HD now.

Sonic Mega Collection+, Sonic Gems, The Legend of Zelda: Collector's Edition, and Mega Man Anniversary Collection are all solid compilations.

aren't you a big fan of Metroid? what's different about prime?

Well, they made it an FPS, so naturally, as a kid, I wasn't at all happy about that.

Maybe I could go back to it sometime, but I already have a fucking enormous backlog myself.

Anyway,

The Metroid Prime series is worth a try. I wasn't particularly into either of them, but they're rather popular.
Paper Mario: The Thousand-Year Door is one of the best Mario titles of all time.
I would suggest Animal Crossing, but only if you have others to play it with.
Mario Kart: Double Dash!! is probably the least shit Mario Kart game, barring DS.

ill shill for all of these