im a fan of Vortex Diamondbacks
will set you back about $250
If you like those you should check out an Athlon Midas 8x42. Astounding what $250 can buy nowadays. I'd put them up against anything under $500.
I have bought two pair of Vortex Diamond Backs, have not looked into the Viper HD but I'm very happy with the Diamondbacks. Honestly, for me to be able to tell a noticeable difference I have to move into a Zeiss or Swarovski, and then your at a noticeable price upgrade.