Been with Kaiser HMO for decades now. Tried Blue Shield PPO plan once but it was awful in our area - no doctors (we tried for the ENTIRE YEAR to get a GP assigned to us and nobody was accepting new clients despite Blue Shield's "list of available doctors". We gave up and went back to Kaiser. Now have their MA plan (Senior Advantage) and it's been fine.
You have to know how to work Kaiser's system. It did get a lot more efficient when the conversion to e-records, a multi-year process, was finally completed about 5 yrs ago. Made a BIG difference for routine care. Biggest advantage of Kaiser is their own pharmacy and ER depts.
Yes, they are tougher on specialized care. But that actually worked to my advantage when I needed cataract surgery, LOL. Was told I had to go to an optician before getting approved for the opthalmology dept, but altho that was incorrect, it turned out to be a GOOD thing. I got advice from the optician that was essential to making a lens choice that worked best for me. It was an honest "here's the downside" reco that I didn't get from anyone else, even though I researched pretty thoroughly on the Web.
FYI, there's a trick to Kaiser if you're having problems getting care: Kaiser has a Member Services Department. Check the website for their 800 #, or go in person to your main local Kaiser (usually where your GP is). MSD will assign a person in their department to act as your advocate to resolve your problem.