I rank 'em like this:
I honestly like Bennett as a #3 WR more than I like the others as #2 WRs. Part of that is Mr. McNair's influence on that offense. Part of it is that these other three guys have their own issues:
Driver has had injuries and plays older than he is. And he's got Walker and Fergie to compete with. But I'll call him a #2 for now.
Kennison, like Morton, is a bit undersized, which leaves only Boerigter as a big sort of target. Morton and Hall, at least, are very fast.
Muhammad falls victim to the fact that Carolina LOVES to pound the ball up the middle with Davis or Foster. And when they don't run, they've got the speedy Steve Smith flashing down the flank.
Bennett is nothing spectacular but, yes, if Calico is going to miss some time, he becomes even more valuable.