On ranked/lobby
XBL Most frequently I seen in order.
1. Hayabusa (Izuna Drops, flashy teleports, Ninpo blasts, NG series main protagonist, etc etc etc)
2. Kasumi (DoA series Main character, relatively low learning curve character for beginners, flashy teleports, frequently tries to abuse quick jabs to overwhelm opponent, popular DoA female)
3. Hitomi ( Another relatively low learning curve character for beginners, Simple straightforward karate fighting style that knocks opponents away, popular DoA female).
4. Hayate (2nd most common male character I come across after Hayabusa, people love to spam that wind dash, more people use him over his Ein persona, pretty flashy ninja in his own right.
5. Helena ( The higher level players online tend to use her frequently, popular DoA female, most didn't drop her in 5U because she is still good without the FT stuff)
Honorable mention to Rachel, but she had a sudden spike decrease of usage once her foot stomp move was normalized.