No treats from me.
Horses usually only get aggressive around food in the pasture--the dominant horse always gets to eat. And here you are, 'giving up' your food!
Treating makes you look like the submissive horse.
I dislike treating for any kind of work. Treating is a human notion; not a horse one. My horses come to me, enjoy their work, and enjoy my company with no treats or food involved. That's the way it should be. If you're treating your horse to motivate it to work, something's wrong with the training schedule. And if you're training just to motivate it--well, then the horse is training YOU.
If you couldn't tell, I really dislike giving horses treats. ;) They get apples and carrots in their feed buckets, but never from hands and NEVER for doing ANY kind of work. I want them to come to the gate because they want to work--NOT because they see me as a feed bucket. This way, I know when my horses are sore or in pain--they won't come for work.