Which Version should I get?
NTSC-J (1.0) is the best version to get, if you want to play the fastest version for ALL categories. After that come the J1.1 and J1.2 version. Then U1.0>U1.1=U1.2.
You don't want to be playing on PAL cause Yoshi has a different (higher) speed in this version (besides it running in 50Hz) which essentially makes it a different game. Due to 50Hz it is still slower overall, unless you would play on a 60Hz modded console, which would invalidate your run anyway, so don't run PAL, pal ;)
So what is different anyway? (J vs. U)
The Japanese Version of the game has fewer text boxes, which means that a little bit of time will be saved. If you are planning on playing Any% (ACE/Credits Warp), J1.0 is the only version the whole category works on. It's also the fastest version for the Null Egg categories.
In general the text boxes work different between J and U. Whereas in the J Version the text boxes work like "pages" they are more fluent in the U Version of the game, essentially making the time when advancing text differ between different text boxes.
In J1.0 & U1.0 there is a glitch that you can do in 6-5 where you tongue a Ghost Shy Guy before it comes out of the pipe. If you spit it out afterwards it will start flying in a straight line, unlike in 1.1/1.2 where it will take a 'natural' flying arc.
In 6-E there is a room that says 'YOSSY' in the J Version and 'YOSHI' for the U Version.
Further changes include a different Pause Menu. In J1.0 it says "STAR" and "TOTAL POINT" whereas in J1.1/1.2 they added the 'S'. The U versions also have that fix and on top of that a more bold font.
But how do I recognize what version I have?
I am sure you can tell whether or not you have U/J/PAL, but here is how you find out the exact version that you have: You look at the back of your cart and search for a little imprint (Refer the picture, which has a '40A' imprint and is from a 1.1 game). The number appears to be random, so ignore whatever kind of number you have.
- Only Number = 1.0
- Number + A = 1.1
- Number + B = 1.2