I fly Ryanair sometimes, for work and hols. They have an excellent safety record. The only thing to be aware of is that you may be stranded if your return flight is cancelled. They are mostly no different to BA and Easyjet nowadays - all charge for meals and don't allocate seats before check-in without you paying. I have found Monarch to be quite good on some routes, WizzAir for Eastern Europe too, but in general the airports being used/weather and other circumstances outside the airlines control are the usual reason for problems.

The only one I dislike is Flybe (or Flymaybe as I call them). I was just looking at BHX <> Hannover in 2 weeks time ... FlyBe is the only direct airline, I was kind of glad to see stupidly high prices due to a huge industrial show going on. Fine by me, I'll take Lufthansa to Frankfurt or Hamburg and take the train to Hannover Messe station.