I've had Maui Jims, Ray Bans, and Oakley over the years and always come back to the Oakleys. They seem to fit my head better than the others. My wife seems to stick with Maui Jims, she loves them. However, while I'll probably end up with Oakleys again, I am currently looking at others because I had a terrible experience with my one of my last pairs, Crosshairs, I bought. I got them just before we went to Hawaii (from Sun Stop or whatever that shop is called), after two weeks in Hawaii, the rubber on the arms was stretched out and wouldn't stay in place. Reached out to Oakley and was told "sorry, we don't sell replacement parts so there's nothing we can do". I usually buy a couple sets a year, so now I'm looking for something else.
As for where to buy. I try to not buy online unless it's direct simply because there are so many knock-offs and some really good knock-offs at that. If you're getting a great deal on them, they are likely a knock-off. So I stick to the retail stores or direct.