I have flown Ryanair maybe a half dozen times, Easyjet a few, Aegean Air in Greece, but no other value airlines in Europe. Each of my Ryanair experiences was uneventful, flights were always on-time, and I have never had any issues with "hidden fees", "extra charges" or anything seen in the many complaints I see.
I do almost always pay to check a bag, if you are lugging your normal "carry-on" for a couple weeks plus a day pack, you need to bite the bullet and pay to check a bag. The only case I did not was a trip from a "home base" where I only took a small day pack for 4 days, leaving most of my stuff at the rental. Many think that airlines never check bags, so take on 50 lbs, but Ryanair does check, and does charge you. Also you need to print out your boarding pass ahead of time, many think they can get around that, but don't. In the end, my total ticket cost, with a checked bag, is still a cheap ticket, better than other options.
I would recommend Easyjet as well, slightly more liberal rules, but not much.