This is another hard one...so many crazy bass players out there. Burton was a legend, Steve is amazing, as is Myung, and theres a few others that hold their own.
Dunno if he's the *best*, but my vote goes to 'other', and although he ain't really metal, I have never heard anyone play the bass like Les Claypool.
Oh yeah, once the weekend hits, I turn into a party animal, look at this, I was going to go to bed FIFTEEN minutes ago, but NO! Im STILL here! Im hardcore.