Mine would have to be a tie between the Tamagotchi Friends and Tama-Go. The Tama-Go has so many creative features not found on any other Tamagotchi. I love how there are so many adorable figures you can attach to the toy, and how each figure is unique. It really adds a whole variety of games and shops so that you never get bored!

And the interchangable faceplates, man I love them! It's such a great idea. I'd rather buy a Tama-Go and a few figures than a P's any day.
The Tamagotchi Friends is less interactive than a Tama-Go with figures but it is still one of the most enjoyable Tamagotchis to run in my opinion. The sprites are amazing and very well-done and bumping is so much more fun than iR connecting. The fact that you can unlock games by collecting jewelry and bumping makes it even more exciting to play with.

The games are really fun. They are found on the older connections but it still really appeals to me since three of the games are from the Version 4 (including jobs) and Version 4 was my first Tamagotchi ever, making it nostalgic for me.

It's really a perfect version for the comeback of Tamagotchi.
I have a P's, iD L, Melody Crown iD, all the connections, EnTama, UraTama.... but Tama-Go and Tamagotchi Friends will always be the best in my eyes!