Song Writing,I grew up with bonamassa but I have to admit mayer's songwriting is very unconventional for blues,yung poppish heart-warming play of words is simply amazing and his songs evoke a lot of emotion compared to Bonamassa's over-worked traditional formula. Technique wise Bonamassa can give Mayer some pointers but to each his own. Tone wise tough call but I have to go for Mayer, a lot can sound like Bonamassa anytime of the day but to have someone sound like Mayer is quite difficult(despite him being an obvious SRV copy-cat,He has a unique tone). And lastly my argument ender; Mayer slept with Jennifer Aniston fuck it. My vote goes to Mayer.