Thoguh some people recomend the V4, that's presonally my least favourite version of all the ones I've had, I just found it boring, and some of the sprites look weird to me
If you don't wanna go around searching for good deals on ebay or FB groups you can just go and buy a TF's in stores if you think you'll like that version.
If I had to recomend one of the conexions I would say the V5 or V6, they are the most fun to me (the Tama-Go is really fun too but you'd need the figures to enjoy it the most)
the V4.5 also looks much better than the V4, but I have never had one so I wouldn't really know, and getting one is really hard, so if you have a chance maybe goF with that one xD