Pretty irrelevant question towards the actual topic but to answer the question, stats and skill take priority then element should be a goal for far end game. For example, I use my Typhon who is only 2/4 break despite have several eidolons with better stats than her but I use her atk↑ buff that no other event eidolon has right now. Though if she was 0/4, I probably wouldn't use her at all.
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If I had a 3rd SSR dark eidolon on my alt, it'd make for better results but I didn't get Medusa with it. It has a Lv40 Ouroboros (+26) and a Lv40 Apocalypse. Ouroboros has higher atk and hp. Ouroboros shows up on my main's friend support.