The question here is... with whom?
I mean, Supergirl has her own show right now, and in it she knocked Superman flat on his backside. Comics may be a male dominated market right now, but go outside that and the pattern begins to change.
supergirl demographic.jpg
This is the response to Supergirl's TV show. There is a very clear trend that the show is generally better received better by female views than males. Especially interesting is the voting by males and females who are under 18 years of age. The number of votes from males and females is comparable, and yet the reaction is markedly different.
By the way, [and you can verify this yourself using this link - because facts -
https://www.imdb.com/title/tt4532368...?ref_=tt_ov_rt ] this pattern continues to a lesser extent with Legends of Tomorrow, where Caity Lotz leads the team as White Canary. Female views rate the show more highly in general than the guys, though not with as big a difference.
Also interestingly, if you jump over to The Flash it is rated about equal by male and female viewers.
https://www.imdb.com/title/tt3107288...?ref_=tt_ov_rt
So those are the FACTS. What do they mean? It seems both genders are often in sync when it comes to a male lead, but put a female in the spotlight and difference becomes bigger and tends to skew towards the males being less impressed on average. One could extrapolate that this trend would continue in printed mediums as well.
So one could therefore hypothesize about the reason behind the OP's question. First - facts - the current readership of comics seems to be abuot 67% male. This is based on the latest marken research [2017] though three years earlier the poll said they were closer to the same.
https://www.bleedingcool.com/2017/10...n-37-by-women/
That being the case, if the trend from TV shows holds true, female readers will read about characters of either gender, but males will tend to be less impressed by books with a female lead.
In short, Wonder Woman is outshone in the books by Superman because most of the readership are guys, and they don't seem to rate a female lead as highly.