The base versions of Rockstar, Red Bull and Monster (and all energy shots) taste like absolute garbage. I hate them.
But many of the Sugar Free Rockstars taste great (much better than their sugared counterparts, I have no idea why) and the base versions of Full Throttle and Amp are good (and some of the flavors of Amp also taste well)
Full Throttle tastes the best though, by a wide wide margin.
As far as what provides good enough energy, the shots are the best of course, but I've had good results on the energy front from most of them I've tried.
http://i.imgur.com/9mRLVL2.gifv