Greedo, Drakeo and Shoreline Mafia are probably the most exciting West Coast hip hop artists at the moment.
The other factor is that I feel like the West Coast is in a general slump right now compared to even five years ago. The Bay Area sound is played out; the YG/Nipsey (RIP)/Game modernized-classic gangsta rap sound hasn't had any good projects for a while; and Kendrick himself hasn't released anything since the Black Panther OST two years ago.