I had Kaiser for several years in San Jose. In fact, my youngest was born there.
Forget the horror stories of twenty years ago. It isn't like that anymore. I was very happy with Kaiser and the hospital stay was comfortable.
You can change doctors until you find one you like. I never had a problem doing this.
Referrals are usually faster and easier as everyone is in network. I also loved that I could be lots of OTC products at the pharmacy for less than the drugstores.