I don't think any one insurance company is the "best" choice for everyone, as everyone's needs are different.
A lot of people in the windshield repair industry use RLI insurance, although there has been some question as to what is covered and what is not. RLI sells different policies for different needs, so I still believe they are worth contacting. Be very specific as to what you want to be covered for, and go from there. Most will tell you that the rates from RLI are very good, but it never hurts to check around. Just be sure you are comparing apples to apples, and are covered for whatever your feel is important.
There website is:
http://my.rlicorp.com
You can also search this forum for previous threads and posts on this subject. There have been quite a few.