Here are my thoughts:
Jimmy: I'm not a fan of a Strat's bridge pickup. In combination with those Tweed Bassmen Jimmy's tone is on the spanky clean side. Too thin with too much treble for my ears. I wonder if Jimmy has a lot of HF hearing loss.
John: I'm not a Mayer fan or a Two Rock fan, but I really like the tone of a Strat neck pup, so John definitely gets points for taking his solo on the neck, and making it sound so sweet. His guitar and amp combo had a great singing voice, so I voted John.
Gary: Again, a guy who solos on the bridge pickup. Interestingly his bridge pup doesn't seem quite as clangy as Jimmy's. Maybe he's got a custom Strat that runs the bridge pup through the tone pot, or maybe his Vibro King just smooths out the top end in a way that Jimmy's Tweed Bassman doesn't. If I could have voted twice, I would have voted for Gary.
Doyle: Kind of disappointed with his SF Fender tone. To me it sounded like a generic SF Fender that never got driven into the sweet spot. I guess it reminds me too much of hearing myself play.
Just my two cents.