Definitely a Bayonetta Collection. Probably the most logical port to make.
Xenoblade X maybe in the future so it doesn't compete with Xenoblade 2, although I'm not personally interested.
NOT Smash Bros. That is something I really do not wish to see. I'd rather wait for the next one.
DK: TF would be a great fit for Switch.
Also as someone mentioned and as DF, a Metroid Prime Trilogy HD early next year would be a fantastic idea to pump up people for Prime 4.