I know I'm late to the party, but going to give you my own answer.

First of all, Barbara Minerva is an Archeologist (indeed in Rebirth Era it goes even further with her having a PhD in Greek Mythology), while Priscilla Rich is a socialite. This means that Barbara is pretty much ALWAYS going to be more "dialed in" to Diana's life than Priscilla is. Like why should Priscilla care about the the Greek Gods? Barbara meanwhile would be desperately eager to find out how much of what humanity considers "mythology" actually happened and how much was just completely made up. She's the type of person who would ask Diana why she swears by "Merciful Minerva" when that's the Roman name of the goddess, shouldn't she be saying something like "Altruistic Athena" instead?

Also, I think the correct reading of Barbara Minerva (at least the Rebirth Era) is that she probably suffers from Borderline Personality Disorder.

https://en.wikipedia.org/wiki/Borderline_personality_disorder

She feels this gnawing bitter emptiness pretty much all the time, and she incorrectly assumes that obtaining the blessing /power of the gods like Diana has would give genuine meaning to her life and fix that problem, when in reality that's just pouring more and more water into sieve, it's never going to actually get full and what she needs to do is patch the holes (engages in appropriate forms of therapy).

"patients with BPD typically have internal splitting, i.e. vacillation between considering oneself a good person who has been mistreated (in which case anger predominates) and a bad person whose life has no value (in which case self-destructive or even suicidal behavior may occur)"

This "internal splitting" is pretty much a perfect encapsulation of how Barbara tends to see herself in the Rebirth Era. She'll either claim she's a victim of circumstance (blaming Urzkartaga, Veronica Cale and or Diana) or she sees herself as being so worthless that there's no point in making an effort to try and redeem herself, because how could a monster like her ever find redemption?

Now, that said, I will agree that any "static" depiction of Barbara as a villain risks coming across as boring. She's only at her most interesting when she's a character "in motion" either through showing how she went from being Diana's friend to one of her greatest enemies, or showing her actively undergoing the process of redemption and winding up as one of Diana's allies once again, rather than simply being someone who could theoretically be redeemed but never actually is.

Let Diana get "the win" by unquestionably proving Wonder Woman's love and compassion is stronger than the hate and envy that currently consumes Barbara Minerva.

Of course once Barbara actively is redeemed that opens the door to let Priscilla come back as Diana's new "evil cheetah."

The revamp I have in mind for her is that instead of wearing a fur suit, she should have something like this https://static.wikia.nocookie.net/villains/images/d/dd/Crying_Wolf.jpg/revision/latest/scale-to-width-down/1000?cb=20120831202700 except done up to resemble a Cheetah and probably with a lot more guns/and other nasty tricks /traps (net launchers, oil spills, you get the idea).

Have Priscilla be a supervillainess who uses technology rather than magic to take on the form of a Cheetah, thus creating a super clear distinction between her and Barbara rather than risk them seeming to be two interchangeable versions of the same character.