I like them both. Preferebly Pyrrha cause she is a tad easier to use then Omega, but Pyrrha Omega has some pretty wicked combos. I personally like Patroklos or Xiba. Pat because he is simple yet versatile, and Xiba cause he is well rounded. If you want more of a challenging character, I would say go for like Mitsurugi or Yoshimitsu, maybe Alpha Patroklos due to a lot of his moves requiring Just Frames.
@JJr I was actually thinking about Hilde but not too sure about her. I'm terrible at keeping track of numbers and I doubt I can make too much use of her Gimmicks.
@Gaza I've seen Omega in action and I gotta say. That stab of hers is insane compared to Pyrrhas. But they both seem to be very solid in their own rights. I think I may look at Yoshimitsu. I see to many Mitsurugis and I don't have the muscle memory for Apat's stances and just frames.
Well, I will admit Hilde takes more practice than Pyrrha and Pyrrha Omega in my experience. I'd still give her a try though. My other recommendations would be Raphael, Elysium (female mimic), or Ezio, but I assume you know Ezio by your avatar =o.
Hilde is pretty good but her darn charge moves make her a pain. And the Pyrrha's really are solid. I view Omega as more aggresive though, and Pyrrha is a bit more on the defensive. Yoshi is a bit difficult. I haven't figured him out myself, but he is a good choice.