Willie Mays Bat Signed Auto PSA/DNA Authenticated Giants 

Louisville Slugger brand.   (much more rare)

most Mays signed bats are  Adiondack
My guess is 98% of all signed Mays bats (non Copperstown ) that Mays used in his playing days are Adriondack. 
so, very few are LS branded bats. 
I have both versions... and I know.. 

from psa/dna web site on Willie Mays game used back summary:

Much like fellow power hitter Mickey Mantle, Willie Mays alternated between H&B and Adirondack professional model bats throughout his career.  While his Adirondack bats do feature his signature on the barrel, Mays’ H&B bats are of the block letter variety only since he did not have a signature contract with the company.  A small number of the known examples do possess either "W. Mays" on some of his early bats or his full name from the latter portion of his career, but most Mays H&B gamers only feature his last name.  Another interesting similarity to Mantle was Mays’ use of pine tar, which evolved over the course of his career.  Early on, Mays was inconsistent about his use of the gripping substance. By the mid-1960s, that all changed.