I was always a huge fan of DOA 2, and then when DOA 3 came out it surpassed it in every way.
Unfortunately we didn't get DOA 3 on Live.

That being said... DOA 2 is still by far the best online fighter out there. The 8 player arcade rooms are AWESOME! It truly does give you that same sort of comradary & competition that one got from standing around the fighters in the arcades. Put your quarter on the cab, call out "I got winner", and get ready for some great fun.