At a base level, I have a Broad Form Liability Policy thru Dairyland that makes me legal for any bike I'm on, whether I own it or not.
Above that I insure some bikes thru Allstate. They also have my cars and house, but the bikes are a separate policy from Auto. I can negotiate a value with them that includes custom parts and accessories, and covers all of our gear.
Everyone will have a story and these companies are still for profit, but for the most part Allstate has been decent to deal with when problems arise.
When I worked at the Honda Shop, dealing with Progressive was the worst. But that was 30 years ago, so that review is pretty much irrelevant now.