>>12014571
>I bought both legacy collections
Congratulations, you're probably going to have a lot of fun.

>I liked X1 more than the classic series desu, I don't know if that's a common opinion or not
Disregard the popularity of your opinions and just enjoy the games you want.

>which are your favorites/what's underrated/overlooked?
My favorite of the X series is X4.
X2 and X3 are the logical evolution of the first X (the 3rd is specially challenging), and X4 is a big jump in quality in general.
Sadly Capcom didn't manage to produce another title like it, and the following X main titles miss the mark to varying degrees, BUT most of them are still enjoyable and can give you dozens of hours of fun (except X7).

My advice is: keep your expectations in check (don't expect each title to be an improvement), and if by when you're done with the collection volumes you still want more, play the Mega Man Zero games and Mega Man ZX. If you loved playing as Zero in X4 you'll most likely like them quite a bit as well.