A faster CPU will allow higher framerates in more CPU-intensive games. No one CPU is best to pair with it, it's more a matter of finding the balance of cost and what meets your expectations.
You could use an i3, but it may lag some; so an i5 would be best. Technically, an i7 would be best, but it's a bit unnecessary/overkill with the 1050 Ti.
A faster CPU will allow higher framerates in more CPU-intensive games. No one CPU is best to pair with it, it's more a matter of finding the balance of cost and what meets your expectations.