If you had the choice to only be able to play one version of tamagotchi, wether it be a p1, p2, any version of the connections and up, which tama would you pick?
The only Tamagotchi I would use is, in this case, the Tama-Go. I don't see how I could ever get bored of it because of the figures! Having some Gotchi Figures unlocks so many shops and games. Furthermore, I love making faceplates for my Tama-Go, and this version also has the best array of characters. Modern characters like Uwasatchi and Lovelitchi, classic Connection characters like Shimashimatchi and Wooltchi, and even elusive characters like Necktietchi and Pipotchi.
Since this is in Tamagotchi ancestors, I guess I will choose out of vintage Tamagotchis as well: The only vintage I would use is the Osu/Mesu pair. Maybe that counts as two, but they belong together, yes? Mothra is my favorite vintage because of its game and cute sound effects, but its small number of characters might get unappealing after a while. I never had the time to really get into my Osu/Mesu pair, so I'm sure I'd enjoy running it for the rest of my life haha. The characters are really cute and the breeding concept seems fun. Also, you can get different characters on different "generations" (TMP levels), promising even more longer-lasting appeal.