In general, I agree with the top 15, but Chris Farley, Will Ferrel, and Dana Carvey should probably be top 10.
I think Joe Piscopo, Garret Morris, Kevin Nealon, Jane Curtin, Rob Sneider, Dennis Miller, Martin Short, and Billy Chrystal are ranked too low (should be ranked better). And I think Seth Meyers, Jason Sudeikis, Andy Samberg, and Al Fraken are ranked too high (should be ranked worse).
But it's an entertaining list.
http://www.rollingstone.com/tv/lists/saturday-night-live-all-141-cast-members-ranked-20150211