As far as artists who can draw an issue every month without needing fill-ins and guest artists that are currently working for Marvel, I came up with this list. Sal Larocca, John Romita Jr., Stuart Immonen, Mike Deodato, and Mark Bagley. Is that accurate, and are there more?
There are probably more than that, but not many. And even these guys may need a fill-in once in a while.