Lets assess this honestly
PLaxico Burress has incredible physical tools. He is fast, he is tall, he is strong, he can leap over defenders, and he has fluid hips. But Moss has all of those things as well, and is faster than Plax. So even in terms of physical ability (which is the only category in which Plax could possibly hope to equal Randy), Moss is better. But Moss edges even further ahead if you consider the most important thing for a WR- catching ability. IMO, Randy has hands on par with Marvin Harrison's and is actually better capable of bringing in high balls than any other receiver I have ever seen (ever!).
No doubt, Plaxico has suffered immensly from lapses of concentration and not beign on the same page with Eli, which have caused his numbers to suffer. Im certain that with his physical tools, he could belong to the elite. But he has to improve his concentration, he has to catch the ball more consistently, and he has to be more coordinated with his QB.
So Randy > Plax. But Plax is definately > than a majority of NFL receivers, at least in terms of talent, even if most of it goes unrealized.