It depends on what kind of handgun you’re considering.
1911 platform pistols, as well as a few others, can be set up so when fired from a machine rest they will beat most revolvers so far as accuracy is concerned. The reason is that the chamber is part of the barrel, and therefore always concentric with the bore. A revolver has six (or whatever) chambers and it is difficult to have all of them absolutely line up. Years ago target shooters would number the chambers and then test fire to find out which one was most accurate, and use it exclusively for slow fire.
In a center fire pistol the trick is to get the barrel to return to battery each time to exactly the same position. While this is possible, zero wiggle can sharply reduce reliability. Service pistols must sacrifice some accuracy to insure reliability, and for this reason tend to be less accurate then best quality revolvers.
Accuracy is relative. If you are shooting bullseye matches it is of extreme importance. A malfunction may cost you a trophy but it won’t get you killed. On the other hand reliability is far more important in a weapon for obvious reasons.
A revolver offers an excellent compromise between accuracy and reliability, but its capacity is limited in most cases to between 5 to 8 rounds – depending on the particular make and model, and it is slightly slower to reload.
So take your choice. There is no such thing as a free lunch.