I didn't play much Tamagotchi and I currently don't really have a version I hate, but I'd say the V4 is the one I disliked the most.
I feel like there are too much useless features like jobs and this mailbox, UGH. You receive pointless letters several times a day (it makes noises...) and your Tamagotchi gets dragged everywhere without you understanding why until you read the manual. I also don't really enjoy the evolution system, based on skills points. With something like this, you can totally control which adult you will get and it's pretty boring... Sure it's not a bad Tamagotchi and there are also great things on it, but you can feel they tried to make it so complex that it becomes kind of annoying.