My Grandpa and Quail hunting buddy always said if it don't start with a B then it ain't no good. Don't know how true that is but I have owned all three and they were all good guns. As for which is best I think it depends on the model and how it fits you, IMO proper fitting it the most important thing to a shotgun, if it doesn't fit then you won't hit!
Very few Berettas will fit me without major mods, most Remingtons are close and a few minor changes will get them there, Benelli shotguns are usually very close and only require changing shims and spacer to get a perfect fit. I usually shoot autos and in those models the Remington makes cheaper models than Beretta and Benelli do but the tend to be the least reliable, Berettas are usually very reliable but you will most likely have to switch pistons for light and heavy loads. The Benellis I have owned and shot will feed anything from top of the line to cheap, they never stop, also since many models don't have a piston they are a little easier to clean. In the end fit is the important thing, after that I don't think you could go wrong with any of the three.
For sporting clays I chose Benelli, specifically a Legacy Sport with 30" barrel.