I mean, at this point I don't mind going full murder mode on both Ella and Danica.
And on the subject of powers more generally, there are a few issues.
One, the MC really isn't doing a lot with his abilities.
And two, the power creep is nuts.
Danica I admit I spared her hoping for a redemption / harem member route for her, it really doesn't make sense to take the risk of leaving her alive I just did it anyway because I have a weakness for attractive women. I have a save at that choice so I can go back and undo that decision if it turns out to seriously bite me in the ass.
Ella, though, is different. Is she the poster girl for "don't stick your dick in crazy"? Yes. But her motivations are ambiguous rather than outright hostile, she has the capability and has had the opportunity to kill the MC but aside from that one bad ending has not done so. We don't know what her goals are but it's entirely possible we share a common enemy and she's merely doing what she feels like she has to in order to defeat it. Killing her could make things worse, depriving us of both a source of knowledge and a potential ally.
Moreover, I'm getting serious "Broken Bird" vibes from her. We know from Christie and Emily that she wasn't always like this but was instead pretty much a nice and mostly normal girl. Something happened, and it surely has to do with her transformation. Maybe the trauma broke her mind, or maybe she's suffering from a side effect of her powers, but I get the feeling that she's going to be revealed to be more sympathetic once we know more about her. I think that either she's going to be redeemable, or she'll end up a tragic sacrifice, or both.
As to MC's powers, he does seem to have had an intelligence downgrade recently in terms of using them. He's fought more than once without even using his armor, much less progressed more on making steel plate for himself. He's not as creative as he used to be about using or developing his abilities, and in fact he seems to have forgotten some of the techniques he learned. I think it's possible he got a bit overconfident and started trying to brute force his way through confrontations with the abilities he's gotten used to instead of actually creatively pushing his limits like he did when he was starting out. Hopefully getting his ass handed to him several times now will wake him up to the fact that he has to use his brain for effective strategy and tactics and not just rely on power leveling like some shonen anime character.
As to the other powers... well we saw Alexis and Clarke undergo an entirely new forced evolution process that pushed their abilities far beyond what they were. In her inexperience and near-berserk state of mind, she lost her shit and unleashed an amount of power far more than she intended and in fact more than she even remotely considered possible. Maybe those two are the strongest out there right now, or perhaps more likely whoever is out there that's stronger is also more experienced and wily about revealing themselves unnecessarily. Bottom line, she fucked up.
The three new enemies have had their powers longer than MC has, and we don't know how they stack up against Ella but we do know she can kill him easily anytime she wants to. We don't know the full extent of her capabilities either, only that she could handle Alexis and Clarke before their forced evolution but afterwards had a much more difficult time to say the least.
In all, we don't have enough information to know what the real scale is, how much the maximum is and how close what we've seen is to that theoretical maximum. One thing, though, Ella described the monsters who transformed them as far beyond her ability to kill --so strong it wasn't worth even trying. So the original monsters, whatever they are, possess pwoer on an entirely different level beyond anything we've seen transformed humans capable of. For all we know they're some form of eldritch abomination with godlike powers beyond human comprehension.
Regardless, this whole humans getting a portion of their powers thing seems to be a pretty new phenomenon, or if it existed prior it was a lot more covert and not out of control like it is now. Either way, I'm very interested in learning more and seeing how this all plays out.