We've flown to Orlando with Britannia a couple of times before and will be going with them again this July. I suppose that says it all really - we wouldn't have gone with them again if we'd found them that bad!
However, we only use Britannia because it enables us to avoid Gatwick / Heathrow, and we probably wouldn't go in the economy section again unless the price was very attractive.
We weigh up the pros and cons of the price / dates available / departure airport, etc. before deciding which flight to book as those factors are all more important to us than simply which airline.