'Kay my turn. :> I'll go in order of the consoles I owned.
Gameboy (Colour) → Pokémon Red
This is actually a bit of a hard one for me because while I loved Red, I don't think it's the game I played the most. I don't even play it anymore. But it was my introduction to gaming and as the very first game I ever had, it will always hold a special place in my heart so it's my favourite. :D
Nintendo 64 → Pokémon Snap
Another hard one, since I also really enjoyed Super Smash Bros, Mario 64, Pokémon Stadium 1 & 2, etc. @_@ I didn't even OWN this game for most of my childhood--I only bought it in 2006ish. But it's such a fun game and I used to rent it all the time. I just. I love it. If there is one game I wish could get a sequel in the history of games, it'd be this, hands down.
Gameboy Advance → Kingdom Hearts: Chain of Memories
n_n I. love. this. game. I know I'm in a vast minority here, because not that many people who liked the original KH also had a GBA to play this on, and almost everyone who did also hated the battle system but... I loved everything. The graphics were great (for a GBA game haha), the controls were good, and I loved the battle system. Also, playing through for the very first time and not knowing anything was just amazing. "WHO IS THIS NAMINE PERSON OMG D:??" Also has my favourite character of all time in it and gets bonus points for that. But yes, I still play the game every so often these days. It's just so much fun. n_n;
Gamecube → Tales of Symphonia
I almost picked SSBM and then realized that ToS kind of... defined my teenage years. :| Yeah, SSBM was fun and more accessible to most people but ToS is just... amazingly awesome. I loved the characters so much. Before this game, I'd never gotten involved in a (purely) video game fandom before and it slowed me down to appreciate games as a fandom and less of something you play through once and don't touch again. I don't really play it anymore (painful battle system after you've played later games XD) but I still love all the characters to pieces.
Playstation 2 → Tales of the Abyss & Kingdom Hearts 2: Final Mix+
....I cannot pick one! D: I just can't! If you add up the hours I've spent playing both of these games (well over 200 hours each), it's probably the same!
Tales of the Abyss is just... a superb game. It starts off slow, and yeah, the plot is fairly cliched, and the graphics are not amazing, but... the characters. The battle system. Just the way everything is tied together. It's an amazing experience. Jade is my idol. *w* I love this game and playing through it with a friend is so great. Even the tedious sidequests can be lots of fun. The game just has so much character and even though I've played it into the ground, I still get the urge to boot it up and play through again quite often. But I can't. I lost the disc. ;_;
As for KH2:FM+... it's Kingdom Hearts! Again, so many hours went into it. XD; They took everything I didn't really like about the original KH2 and improved upon it. New abilities, new plot, new boss battles (eeee Organization fights! ♥). This game single-handedly gave me carpal tunnel, I'm not even kidding. (I remember the beginnings of it started in the Castle Oblivion hallway-lookalike in the Cavern of Remembrance.) I know that shouldn't be a good thing but it's kind of a testament to how much I played. :P Additionally, factor in that the + in the name of the game refers to the remake of Chain of Memories that was packaged with it and sdklfds HEAVEN. They remade my favourite game with a horrible 3D camera and gorgeous graphics. My favourite characters taaaalked. eeeeeeeee. I still get giddy thinking about the weeks and months leading up to the release of this game. Seriously. Now I want to go play it again.
Nintendo DS → ....The World Ends With You
I am quite tempted to put KH 358/2 Days here, I'm not gonna lie, but I didn't enjoy the game as much. (Although I probably put in twice the hours since I fully completed it twice.) But TWEWY? I just loved it. The music was catchy, the plot was intriguing, the sprite graphics were top-notch, and the gameplay... was so much fun! And best of all, it had Pi-Face! :> He made math cool again and then you get to steal his pants. And hat. And jacket. And bandanna. Awesome. It takes a while to get used to the battle system but once you do, it's immensely fun. Especially with Joshua's jesus beams. 8) Also tin pin. And Another Day. skldfds win.
Nintendo Wii → Super Smash Bros Brawl
I don't... play anything else on the Wii... so... this kind of gets in by default. But I have poured plenty of hours into it! My friend and I are sooo close to having a complete file on his game. D: And when we're bored we'll make fake tournaments on it. idk. It's lots of fun. I don't play anything else on the Wii but I have two games I've yet to touch so maybe this'll change one day.
Playstation 3 → Little Big Planet
I don't have much on my PS3 and this may very well be overtaken by FFXIII by the end of the month. XD; But LBP is so much fun to play with other people. And with custom levels built by other people, it's really amazing and eye-opening too. Some people make super creative, fun levels, and others make mechanical masterpieces. It's crazy. @_@
Xbox 360 → Assassin's Creed II
I loved the first game and the second was a great successor. It fixed everything that went wrong in the first and added plenty of its own. I've only played through it the one time but I watched most of my brother's playthrough, and all of my friend's playthrough (so far) and I just love the game. The glyphs were probably my favourite part. n_n
Honorable mention goes to Bioshock.
PSP → Kingdom Hearts: Birth By Sleep
The reason I wanted a PSP in the first place (though technically not quite the reason I bought one). This game is amazing. It's on par with the KH console games and really holds its own. The plot is interesting, the characters are way too lovable, and the graphics are gorgeous. (Also music is A++ as usual.) If you own a PSP, you should own this game. n_n I don't want to say tooooo much though, since it's not even out in English yet. XD;
oh my god how did that get so long? ._.;;;