Just a reminder: this thread is about insurance BROKERS. Insurance brokers represent the client (the pilot) to multiple actual insurance companies (who never deal directly with the pilot). You want to pick an insurance broker based on their knowledge and customer service. In principle, all insurance brokers will get the same quotes for the same pilot. In practice, there may be small variations (broker may take a smaller commission, for example) but the single largest variation is usually the fact that the insurance companies, in an effort to keep their cost and confusion down, will often refuse to quote one given pilot to more than one broker. So my advice is to pick one broker with a good reputation for knowledge and service; discuss your needs and desires with them, and ask their advice; let them get quotes for you. Asking multiple brokers is counter-productive, as they will be unhappy after they've done the work and find that companies will not quote them because you've already been to another broker.
Exception: AVEMCO does not use brokers, they are (the only) "direct writer". Send them an application if you wish (in the past, for me, they have come in much more expensive than the broker-found companies).
For the record, I use Gallager (nee NationAir) and have always been happy.