I use Travelers right now because they were the cheapest. I can't complain, but I haven't actually used their service, I have just paid for it.
Actually, I have never used auto insurance with any company - no claims, but then they run the DMV check...
Whenever they try to jack the price up, even by a little, that's my sign to go shopping. Somebody will beat them.
First insurance on my own (not attached to my parents' policy) was Geico. Started out dirt cheap, but they jacked my rates up majorly due to a couple infractions, despite no claims. I decided to get insurance through an independent agent who offered insurance from multiple companies. He got me a great rate to start, lowered it each renewal, and was super responsive and on top of things. Really, really great company to deal with in every way. Unfortunately though, when I moved from NC to AL, I had to seek new insurance as my agent wasn't licensed down here. I actually sent him a thank you note for the great service over the years when I had to drop it due to moving.
First insurance company down here was Esurance. Just wanted it done quick because I had other moving issues to deal with. Their online quote was good, then after signing up for the insurance and actually paying the first premium, they come back and say "it's actually going to be more." I make my displeasure known, but pay anyway because I couldn't deal with getting a refund/getting different insurance at the time. They lowered the rate slightly at the next renewal (by like $10), but then at the renewal after that they decided to try to clean me out. Nope.
It just so happened at the time that my bank sent me an email or something offering insurance services through a variety of companies. I called them, and they set me up with Travelers for a much lower premium than I had been paying through Esurance. MUCH lower. I have been using Traveler's since with no complaints, but as with the previous companies, they have never paid anything out, so the service should be good. Geico and Esurance didn't get that - their formula was to bait with a good initial price and online convenience, then get greedy and find anyway to shake some more out of you.
Personally, I have learned to go for independent agents who shop multiple companies, or go through an institution who does the same like a bank you already use or your employer. Going directly to the insurance company and using the convenience of their website is a good way to be seen as an ATM. They think you value convenience over all else and don't have time to shop, which is often true, so they try to clean you out however they can.