You asked for other "good" baritones, and so I named a couple that are fairly known. I could name some more that I think are good(like Matt Hammit of Sanctus Real, for instance) but you probably wouldn't know who they were.
One thing: you're absolutely CRAZY if you think Stapp sounds like Brad Arnold(that is his name, right?) I hear no vocal resemblence between those two, so I can't understand why you think Stapp and Arnold sound anything alike. Yes, I might give you the Vedder comparison, but no way will I give you that comparison.
BTW, I don't listen to Stapp all the time(I've been more into U2 and a bunch of other artists lately) and I've only been a Creed fan for 3-4 years. But when I hear just one or two seconds of him singing, I know exactly who it is. Even my niece and nephew do(and I have put them to the test on that.....and they only know one or two Creed songs). I still think Stapp has a fairly unique voice.