Who is everyone finding success w/ at fifth rotation spot?

It feels like most of us have some combination of Donaldson, Pedro and Randy by now. My fourth guy is a wildcard Bob Gibson. The fifth spot is still a big question mark for me. Had some success with Rizzo until it seemed like everyone crushes him. Then switched to monthly Darvish for a time but it feels like everyone figured him out. Nolan is cheap now so I’ll try him out but it seems like it’s just a big toss up.