Theres some good new games. but sadly not all fit plus games are on U. like the bird and skateboard. so id play both.

Largely dependent on what activities from Plus you enjoy. If you like playing the skateboarding game for example then you should still hold onto Plus. There are some good activities in U though, plus the Fit Meter actively incentivises me to exercise more. I'd say keep both.

Why not get both?

as someone who did, yeah! just some exercises are gone (skateboard and juggling my beloved)