I picked the V3. It's very needy and it's very easy to get it to 99 lbs. and it takes a LONG time to work it back to a healthy weight. The characters aren't that great and it's very boring.
The V4 was quite annoying. I got so many freaking poos and money stolen! Plus choosing a job was boring because you had to have a certain amount of skill points and no one wants to play games for hours on end.
I'd have to say v5, I kinda got annoyed cuz there is no weight, so it's really boring, plus, you can't even connect w/ other version! I like the older versions cuz they are so original! I love the v2 and 4.5. V1 is okay too.