The SNES version(and Genesis) of Micro Machines is almost exactly the same as the NES version(it may be exactly the same). I recommend either system. The N64 version, well, I have not played it for a long time. All I remember was I liked it, but not as much as the others. Now, The first Micro Machines game for PSX was fun. It had a 8 player version if I remember correctly. I played it with 3 people and had a blast when it came out. I had a good time with it on one player, but the multi-player was a blast. Just like the SNES/NES versions. The PS2 version wasn't as good in my opinion. I was really excited when it came out but only played it a few times. It just wasn't as fun as the others.

So here are the versions of Micro Machines I have played:
NES/Genesis/SNES = As much fun as you can have with your clothes on
GameBoy = same fun, but may be alittle harder. Not sure if the multi-player is included.
PSX = Great fun in Multi-player
N64 = Just OK, I need to play it more to really remember
PS2 = I would pass
PSP = just got Micro Machines V4, but have not played it yet