UA is vastly inferior to DL at this point. No ifs, ands, or buts about it.
I've said this before, but my wife had some travel last year to DEN and SFO. So, we match her over to 1K and she flies UA a few times. After every flight, she'd say "even with the connection, I should have taken DL".
But you are in IAH, so not sure what the alternative is.