I always tell my alliance members when I am giving my opinion on a hero that if you only have that one hero then it is a great hero. However, I think in general people mean that there are better heroes in the game and if you have them or the means to get them then it is not the best idea to max them. In your case, those aren’t horrible. I have Elena as well, I got her as my 2nd 5* after Khagan. Luckily the day I decided to max Khagan over Elena, I did a single Atlantis pull and out popped Mitsuko. 0.3% chance as a non-featured hero too!.
I do like Elena and Khagan but there’s an example of what I mean. Given those 3, Mits is the best. But before I got her, I decided to max Khagan though I got about equal votes here in the forum for Elena as well. I also have Obakan and Domitia and chose to max Domitia. Again, if I had Sartana or one of the crazy purples like Ursena, Seshat, Hel, Kage, etc. I would have benched her but given the choice of Obakan and her, I maxed Domitia and really don’t regret it.
Hope that clarifies things and I think that is mainly how others compare as well. Like others have said, the best 5* is the one you have.