If you could only choose just two types….

inspired by a post in another thread..

you’re air force has a lot of 70s-80s era aircraft and needs to be updated, it will get Pak-Fa, but that won’t come in meaningful numbers until much later.
you have a variety of options that could provide something updated/new right now until you can get the Pak-fa in numbers.

But you can only choose two types. Which would you choose among these options and why:

Su-35S, Su-30SM, Su-34, Tu-22M, MiG-29SMT, MiG-31BM