I have only ever experienced EasyJet and I can't fault them. See it for what it is - a flying bus - and you'll have no complaints. You get on, you travel to your destination, you get off. Simple as that. And, if you book a little sooner than 5 hours before you fly, it can be quite cheap too
In comparing EasyJet with Ryanair, I would say EasyJet is more likely to get you closer to where you actually want to be as it relies a little less on provincial airports that can be 75 miles from the city you are allegedly flying to. I have also yet to hear EasyJet grumbling about ways of persuading passengers to fly without checked baggage, which I know Ryanair is actively considering and could turn out to be a complete pain.