I've seen Genge dominant opposition tight heads in a way I haven't seen since Sheridan, but I've also seen him get in a bit of trouble too.
I don't recall seeing Marler struggling with his opposite number.
I'd take either personally, but given how Wasps tend to play, it'd be nice to have the power/aggression of Genge in open play.
That being said, West is a very strong scrummager, and Martinez looked very good before his injury.
Right now I'd take anyone that's fit