Probably the 10-10 scale from RCBS is what I consider one of the better ones.

But if you want the best, thats a big term. I can tell you anything from atomic scales to $800 counting scales.

As far as who is accurate, what I did is buy a scale calibration kit with calibration wieghts. My 505 RCBS was dead on down to .1gr. And a 505 scale don't cost much either.