I don't know what your budget is, but I love my Bryston 3b. The Hafler 500 is an awesome performer... capable of crazy low impedance...and is nearly bullet proof, but if it goes, it's expensive to fix. The Kenwood Basic M2 is a surprisingly good performer. Vintage Sansui amps sound incredible, but they are pricey. I'm borrowing a Technincs SE-A50 from Tom that is a huge surprise to me. Sounds every bit as good as a Nakamichi PA-5. I'm not a huge fan of Adcom (sound/reliability), NAD (reliability), or Carver (Sound/reliability), but that's just my experience. Of all the amps I've owned (which isn't many compared to a bunch of other members), My top 3 are McCormack DNA1, Bryston 3b, and Onkyo M-508.
Hope this helps and doesn't further confuse your attempts at narrowing it down to 1.