"Best" is a dangerous word to use when discussing bases and rings.

Murphy precision titanium bases are as close to the best as I can think. I run one on my 338 lapua....30 MOA.
Nightforce, seekins, zeiss, are all top of the line. Leupold, warne, weaver all decent too. Just depends on how much you want to spend. If you want to shoot longer ranges, you may look at at a 20 MOA base....of course this depends on your scope and what your need is.