As you know, there are two main carriers in the U.S./California:   AT&T and Verizon;  there is also T-Mobile to consider.  My experience in California is that Verizon is one of, if not the best!

I'd ask your colleagues in Sacramento & Red Bluff which service they have the best luck with and go with that.  - - I used to live in Redding way back when... nice area for sure, although a tad hot this time of year! -  Good luck getting better service!