I have had both types of guns fail. I have owned and shot and traded a lot of guns over the years. Most of the failures with revolvers that I have had, were due to factory defects in the guns themselves and were pretty much known right away. Outside of that I have had a couple of hammers break, I have had some misfires because of too light firing pin strikes due to guns being tuned to light to get a light trigger pull. And I have seen a grain of powder get under the extractor and lock up a revolver.
However, once a revolver is tested and found reliable, then they were usually very reliable from then on.
I have had and own several very reliable semi-autos, but I have also purchased several that were unreliable and those defects were usually know right away. Outside of that, I have seen a few jams due to bad magazines, bad ammo, had a few extractors and firing pins break on heavily used guns. But generally if the semi-auto is reliable it usually stays that way, unless it gets pretty dirty or encounters bad ammo or a change in ammo.
I would give a slight edge to the revolver for average use, but actually in heavy dust or mud, a good old 1911 might surprise you with it's reliability, vs a revolver that gets muddied.
Once proven reliable, I have pretty good faith in either weapon. But frankly I have had and seen a lot of lemons new from the factory, I have even had my share of Ruger Singleactions that had problems due to quality control from the factory. As far as new guns go, I have had the best luck with Glocks, over just about every other brand, to be out of the box reliable. I didn't say they were my favorites, just seemed to usually work out of the box, which is a lot better then I can say about a lot of others.
One thing I don't agree with is that a gun needs to be shot in, before it's reliable. Yes, they need to be shot, 200 rounds to prove they are reliable, but It's been my experience that if they are unreliable to start with, they usually remain that way until fixed, and some are pretty hard to get fixed IMHO. A good gun should work right out of the box, but many don't.