Any reason it has to be those two? If its a gem you have the option to save it for a better cosmic champion (not that these two aren't great cosmic champs). Unless you have it in overflow, I'd save it for sure.But to answer your question, I'd go for Angela. Among other reasons, she has great damage and a useful synergy with Heimdall which you definitely need for 6.2.2. Mr. Sinister.