True that, but I know pre crisis Supergirl was head and shoulders equal with Superman in every way. They even had fun competitions like races and such...
Haven't seen any reason so far to believe that's less true post crisis.
Pre-Crisis, Superman was stronger and Supergirl faster, I think. That might still hold true.
She's learned to hold back some... but even if she's at full, it's not like Clark holds back a lot against Billy, and it's been shown that Clark can tune it up past her level. Clark's a better HtH fight.
CM wins.
Diana and Maxima and Barda would have a much better shot among heroines.
As I recall, she was pretty buff during the v3 JSA run. Beat down a mind vontrolled Superman, while fighting other villians like major force and Black Adam..
For some reason, her more recent portrayals have her getting practically swatted aside by Supes and Adam, but I think that's lowballing her considering her previous showings and power set... (She's supposed to be about even with Supergirl, right? But a better fighter?)
Power Girl... I'd say she might get the odd win, but does have the magic disadvantage unlike the trio I mentioned.
Better fighter than Kara (more experience with her powers definitely), I think a somewhat stronger, but not the kind of skill-monster Barda or Diana is.