I'd definitely take a Superman show over Supergirl at this point. No bullshit government conspiracies, no mind wipes for literally no reason, no pretending that the obviously evil Luthor isn't evil, no more Catco related crap, etc. Just bring in the guy who played Superman on Supergirl (and presumably the woman who played Lois), maybe hire a real Lex Luthor, and they'd have a potentially great show, and the first real Superman live action TV show since the 50s (Smallville didn't have "Superman" in it, and Lois & Clark was a romantic comedy where Lois was the main star).
Supergirl has had some great moments and great characters, but its always been filled with a lot of crap that frequently outshines to good stuff. While I've grown to like this version of Supergirl a lot as a character, her show is a rollar coaster of quality that has been dipping down into mediocrity (or lower) way too much. A new show with Superman could be a fun breath of fresh air at this point.
That said, I'd also be up for cancelling Arrow or Legends of tomorrow and replacing one of them with a Superman show, although that would probably be thought of as an over saturation of Kryptonians.