That's a pretty broad question. Best for what? What type of scope are you using? What type of shooting do you do? Hunting, competition target, military/LE sniping?
I've always had good luck and been happy with standard milled steel Leupold bases and rings, and thats what I have on most of my hunting rifles. Although one of my rifles has Weaver rings and mounts. Personally I think shooters place way too much emphisis on rings and mounts, and spend way too much money on them than they really need to.
I have a friend who bougth some aluminum Leupold Rifleman rings and mounts to go with his Rifleman scope a couple years ago. He said they were pretty inexpensive and he hasn't had any problems with them at all.
Avoid detachables on anything but a safari rifle. If used on a long range hunting rifle, you'll be resetting your zero all the time.
There are still some who insist a scope is not needed for the type hunting they do, ignoring the advances of the last 150 years in optical sights. (Even the ultra-conservative US Army has adopted optical sights.) The idea that in some special circumstances open iron sights or aperture (peep) sights might be more useful is not lost on me, but with the inevitable advance of age comes the reduction in visual acuity needed for using iron sights.
I believe that many who completely resist the idea of...