First and foremost: what's your price range?
Second: what kind of sound do you like? Warm, sweet, and laid back? Cool, forward, dynamic, and as detailed as possible? Those are what I think of on the opposite ends. e.g. McIntosh & Sonus Faber vs. Krell & Wilson.
I think ICEPower amps are a popular choice. I use a Bel Canto S300 along with a tube pre for my BE-718s and like it quite a bit. A little warm and sweet -- moreso than other ICEPower/Class-D amps like W4S or Nuforce, or so I've heard -- but still a lot of detail and good speed and punch, unlike tube amps. I also appreciate the low power consumption and heat dissipation a lot. An S300i integrated would run about $1k used.
Just make sure you're giving these power hungry guys enough juice. Absolutely no less than 100 WPC SS. Usher recommends 200 W. A lot of tubes, especially SET, are out of the question.