Which Insurance Company.

To get an umbrella policy from USAA, they made me switch from Hagerty to American Collectors. This was about 4-5 years ago. I checked a few months ago, and American was about 15% less. I never had a claim with either, so I can't help you with that. YMMV.
Unfortunately, I have had to file a claim with American Collectors, and that went as smoothly as it possibly could have. I have nothing but good to say about American Collectors. The best part is they didn't give me any grief about why I had my car out when a deer hit it. I've been told Hagerty will.