New player, Baretta or Aria

Hey guys, I'm a new player (rank 28) and I have two cards that I know are solid but I'm not sure which to invest in first. They use similar runes and I don't exactly pump out 5*s at the moment. I currently run the following:

5* Wind Undine 5* Shannon 5* Michelle 5* Ramagos 4* Bella (just got yesterday)

I will post my box but my notable cards besides those appear to be Baretta and Aria. I'm currently done with the scenarios besides a couple on hell, beat gb7, auto 6. Beat db6 and in the 30s on ToA. Any advice would be greatly appreciated! Thanks.

http://i.imgur.com/lHqUWfD.png