Mechanically, there is more to go wrong with an auto than a revolver. However, if something does go wrong with a revolver it's more likely to be catastrophic, i.e., explode in your hand. With an auto, in an emergency situation you have to consider, is there a round in the chamber? Is the magazine properly seated, or in my haste to get the gun out did I accidentally hit the mag eject button? Does it have a safety, is that on? Will it feed the next round, or eject the spent case properly? Lot's of moving parts and at any time one of them can go a little awry and cause an issue. A revolver, in an emergency situation, is simple, pull the trigger and as long as the cylinder aligns with the barrel and the hammer strikes the the primer, it will go bang. Both of those issues are ones you can determine well in advance of when you need the gun to work if they will be a problem.
All that said, today's autos at least are generally excellent and reliable. I've had most of the issues I described happen to my Glock when practicing with it (except for the safety, it doesn't have one), but if I were to need it I feel I can rely on it. One other thing to consider is if you want a gun that will sit loaded for months at a time, then if it's an auto you'll at least need to pull the bullets out of the magazine periodically, switch out with another mag. Leaving them in the mag for extended times can affect the spring, and that can lead to feed problems. So for sure, if it's a gun that just sits in a drawer for months on end, and you don't want to pay any attention to it, then a revolver is better option for that reason if no other. But if it's a carry weapon that you will handle regularly, take to the range and clean it periodically, keep it maintained, then an auto is a perfectly fine option, despite all that I've pointed out.
