Madden (EA): I love football, I love the graphics, animations, level of complexity and the fact that they can essentially push out the same game with 2 game improvements every year that somehow make the game very different to play, and roster updates, and end up being the best sports franchise in history.
MLB The Show (SCEA): I love baseball... I think that's enough said. I just freaking adore baseball, and would play any kind of game, if only they added sabrmetric functions into the game, then I would probably live in The Show... but they haven't, so I continue to have a life.
Mario (Nintendo): How can you beat this side scroller. No matter how many games they push out, there's always something new, even though it's the same old game. 7 Stars is one of the best RPGs ever, and the side scroller games are just fun as fuck. What more can I say?
Sonic (Sega Sonic Team): The only reason to buy a Genesis... enough said. In the early 90s, the only reason Sega was still in business, trying to push shitty games with Sonic was their only way to profit. No one owned a Genesis for Revolution X, nor did they own it for NCAA Football, where you could score a safety and have it added to your points total. Thank god for emulators or no one would ever play this game, since the Geneis is a piece of shit that has 1 good series of games.
Final Fantasy [especially 7] (Square Enix): Can't think of a more developed RPG, one so ahead of it's time in everything from story to graphics. Revolutionary graphics for it's time, enough can't be said about what they did with a system like the PS1. There is a reason no one remakes this game, because it's pretty much perfect, even if they characters don't have mouths.
Pokemon (Nintendo, The Pokemon Company): The first 150 pokemon were cool, the next 100, eh, not so much, the other 240 I have no idea where they came from. What the fuck is a Spoink? It's a blob with a spring on the bottom. They ran out of ideas, not really for the story, but for the remaining pokemon. The first 150 games were interesting, replayable and completely new. Such a simple RPG, with amazing replay value, and so much to accomplish in a very simple world left you feeling like this game had you accomplish something.
Zelda (Nintendo): You're granted a very likable character with the same usual story of saving the princess. Thing is, you get this nice feeling when you're accomplishing things in this game, and it's very intuitive and user friendly, so it was quite ahead of it's time. Very different from most games, generally had a complex map that was not too difficult to figure out, but was vast. Weapons in the game had many purposes and are generally sick, who wouldn't want a hookshot that can swing them from place to place? Sure beats the hell out of playing Batman, possibly the worst game ever.
Grand Theft Auto (Rockstar): Killing people is fun. Having no remorse about it is more fun. I don't like war games, and general first person shooters, so it's a nice way to let me get in on that fun without making me play an FPS. Maps are huge, there are a million things to do, by the time you beat the game, you've probably only completed 50% of the things you can do in the game, so the gameplay lasts for hours upon end. The different games in the franchise are generally very different from putting you in the streets of Compton to a clone of New York (San Andreas and GTA IV).
Tetris (Various): So fucking simple, I'm really damn good at it (probably because I'm Russian and have been playing since I was three). Two things we Russians do is kick ass at Tetris and replace people's water with Vodka when no one is looking, not that we'd be able to tell the difference. It's so simple, has a ton of strategy combined with fast finger movements. You couldn't write a better recipe for a game if you were Julia Child.
Civilization 4 (Firaxis Games): The only real time strategy game I'll really play. A great blend of history and role playing. Do everything from wipe Ghandi's people off the face of the planet (don't tell me you've never thought of this) to orchestrate trades with Catherine the Great who died nearly 500 years earlier. Build your civilization from scratch, making the decisions that will best impact you for the future. Can't decide whether to build the Great Wall or learn horseback riding? Heck, do both.
So concludes my favorite 10 games of all time. I may have left something important off the list, or not, but this is just a rough estimate anyways, so I'm sure you'll catch my drift of what I like.