V3 is a bit more like some of the vintage Tamagotchis, but with the new features like the 'shop' and IR connection. It's a bit more no frills than the V4 (which has more features again, like the 'mail' and the Tamagotchi going to school and work) but more complex than a vintage or earlier connection. It depends on what you're looking for in a Tamagotchi
This choice is so difficult as I adore all of these versions. Eventually I still chose v4, because there are some new for a good price on ebay; like these.
Hmm I would have to go with v3 coz personally I like simple tamagotchis like the v3 and the tama-go. I mean you don't have to make them go to school/work; just get money from playing games ( I'm VERY lazy lol )