I'm sorry I can't be that much of a help, seeing how I've never even heard of the B&K and Rotel before (not sold anywhere near my place, and I don't interest myself in stuff I can't go and test at the store).
I have however had experience with NAD, and out of the stuff available here which is Pioneer, Anthem, Yamaha, Paradigm, and Bryston. I'd say it's only second to Bryston. Now mind you I have done no blind tests or anything, just same speakers and switch the amps in the same room. But of the first 4 I've listed I couldn't really tell a difference. NAD and Bryston seem to be the only one I would actually be willing to argue for in a manner more befitting an audiophile forum. So I don't think I should do that here... no blind test and all.
Out of the two remaining, which is NAD and Bryston, again the two are almost indistinguishible, what little I thought I differentiated, I'm inclined to dismiss to my prior knowledge of the fact that Bryston uses best materials for every component known to man, never settling for less and just letting the price tag take care of costs.
Now I must point out that NAD is out of my personal price range, however I have recommended it to my friend (sorry don't recall the model atm, something in the middle of the price range) and he has been very satisfied. He uses NAD to drive a pair of these:
http://www.klipsch.com/products/details/rf-82.aspx. And in all the time since he bought NAD he never expressed interest in looking at what else is out there.