In the 90's they were about even.. I feel like Sacramento should be mentioned as well... they were putting out a ton of heat in the 90's. They brought a darker vibe to gangsta rap that separated it from G-Funk and Mobb Muzik..
The early 00's (from about 2000 to 2005) I'd give to the bay, they had nothing but heat until the Hyphy bandwagon shut everything down...
Keak the Sneak "Counting Other Peoples Money"
Messy Marv "Disobayish" and "Tattoos, Bandanas, and Tongue Rings"
San Quinn "I Give You My Word",
Turf Talk "Street Novelist"
Mac Dre "Thizzelle Washington" "Dreaganomics" and "Genie Of The Lamp"
Guce "Pill Music"
Casual "Smash Rockwell"
The Jacka "The Jack Artist"
and probably more that I forgot...
From the late 00's LA took it back, can't hate. I don't like alot of the new stuff coming out of the bay or Sacramento.