I have three different massage-type brushes (varying size bumps/bristles on it). Unless I'm in a hurry, I generally spend 30-60 minutes grooming before I ride. Most of that is with the massage-style curries, and then with a couple soft brushes and a face brush, which includes lots of ear scratching.
With the massage brushes on his neck, he leans hard into the brush - I often put the full force of my body into him (and if he suddenly decided to move away I'd end up sprawled on the dirt, lol). On his belly, he gets the top-lip wiggle going on. Everywhere else, his head lowers down and he practically falls asleep.
I figure it's the least I can do in exchange for the hard work I make him do, especially if we're working on something difficult.