Shame, never played that either. Is it recommended to play xenoblade on the Wii and the wiiu before playing xbc2? I might just play the one on switch and not bother if it doesn't matter too much.
Basically reiterating what the others have said, but I'll add that there is a link between XC1 (Wii) and XC2. It's not revealed until the last 1-2 hours of the game though, so the games themselves are essentially self-contained, just that there's a scene towards the end that will have more impact as a fan if you've played the Wii game. If you don't care much, you can't go wrong with starting with XC2 though.
I never finished XCX (Wii U), but my understanding from the ~60 hours I played and from what I've read is that the story has no definitive connection to the other two, so it can treated as a separate story entirely that can be played in any order.