Most of my flights are made to places I've never been before, just for a break, and to travel around. For that, Ryanair is unbeatable. I'll have been to every EU country by the end of this year, and that's all thanks to Ryanair. If you accept you'll be flying to a random airport in the countryside, check-in online, carry only hand luggage and pay using Electron (I got this card purely to beat Ryanair's payment charges) then they are brilliant. I haven't paid more than £10 one way for any flight with them this year, and am rarely delayed.
If my trip has a point (i.e. visiting parents at Xmas, where a suitcase is necessary, or to a specific place where my football team are playing) I'll use Ryanair if they substantially cheaper all-in... if not, then there are tens of other airlines out there who I'll happily give my business to, if the fare is competitive.
They are certainly getting sneakier with their fares though... on some routes (Dublin especially), you can have £0.01 fares which are no taxes, £0.00 fares at £25.91 taxes or £15.00 "special offer" fares which have £4.99 taxes. So the £15.00 base fare is cheaper than the £0.00 fare, but the £0.01 is the cheapest of the lot! I wonder how many people look at this before pressing "book"?