V-brakes are the most powerful rim brakes of all time, which means they're the most powerful brakes you can put on a bike. More power, yes, than hub-disc brakes. Easy to set up and maintain, easy to source replacement pads for, good all-around.
Deore V: Shimano's best-value line, and these brakes are just--as good as brakes need to be.
XT V: A notch above Deore, no better mechanically, but slicker brake pad holders and finish.