-Mario Kart (Super NES):  The one that started it all.  Racing skill is the key to winning in this one, not luck.

-Mario Kart Super Circuit (Gameboy Advance):  Excellent first step into the world of handheld gaming

-Mario Kart 64 (N64):  Entered the world of 3D--introduced the Blue Shell!

-Mario Kart Double Dash (Gamecube):  Two drivers, two power-ups, and character specific power-ups

-Mario Kart DS (Nintendo DS):  Online play, mission mode, and drafting, designing your own decal

-Mario Kart Wii (Nintendo Wii):  Better online play, motion controls, motor cycles, and tricks

-Mario Kart 7 (Nintendo 3DS):  Lucky 7, Crash Team Racing styled boosts, 3D graphics, gliders, underwater racing

So which game is the best and why?

I voted for Double Dash but I think it's greatly influenced by my situation when I bought that game. I was still living at home with my two brothers so we played the hell out of that game, always doing the All Cup (all 16 tracks in random order).

The battle mode was not as fun as Mario Kart 64's but it was MILES better than what we got in MK Wii. Also the shine thief variation was a great addition.

Mario Kart: Double Dash
Mario Kart 64
Mario Kart (Super Nintendo)

Double Dash was great to play together.

Super Mario Kart SNES, the original followed by Mario Kart 64 because it was the first in 3D making it more original than the following games.

MK 64, that game was a blast!

Btw, didn't know MK Wii was also on the PSP ;)

Super Mario Kart (SNES). Not because it started the series, but it was actually very very very hard (but fair) to beat the game. I was so annoyed after Beating Mario Kart 64 in just one weekend. Last year, I played the SNES version again and I totally sucked because the newer entries to the series had softened me.

Mario Kart Wii (PSP)??? This is a joke.

I voted for MK64. Double Dash already has too many votes...

MK7 hands down because the tracks are amazing... by far the best in the series! Also the 3d makes you feel like you're really there.

Double Dash is my second fav cause the tracks are great and i really enjoy the drift/boost in this game.

DS is my favourite, but I haven't played 3DS yet.

I only quit playing 3DS when snaking to beat staff ghosts gave me carpal tunnel. Seriously.

I would rate them DS > GC > Super Circuit > 64 > SNES