I would highly recomend the Bryston. In my opinion it is the most satisfying musically. Just my 2 cents.
All are great. I have been a fan of Krell and McIntosh for years. But you really have to listen for yourself. One of the best systems I have ever heard in the last 20 years was an all McIntosh system. The funny thing is most "audiophiles" don't consider McIntosh "high-end". The bottom line is you are the one who has to live with the equipment so give them all a listen. If you can't listen to all of them make your choice on which one you can hear. The best thing would be to take an amp home for the weekend and give it the run though.
I can't comment on which of the three you mentioned is best, but I can tell you that I currently have the Bryston up for a NO RESERVE auction right now here on audiogon. I never even took the thing out of the box and hooked it up or else I could render an opinion. Anyway, I suspect it will go for far, far, less than 4K and it is unused. Check it out! The auction ends this coming Monday, November 18.