hmm, i only own a tamagotchi friends and not a tama-go.
I really like the friends!and the tama-go has figurines to place on top and stuff, so i'd say tama-go, though i'm not sure, as i don't own a tama-go.
If i would like the tama-go better, i wouldn't like it that much better, i like them almost equally and they're both awesome in my opinion