My trainer swears by Succeed, she's tried everything else and say that its the only thing that works. No personal experience yet, will most likely put my ulcer prone horse on Succeed after this BPR treatment.
I've used SmartGut sucessfully for a TB suspected of mild ulcers. IMO Succeed is just too expensive to warrant trying, but each to their own. I've also used SmartDigest Ultra on a different horse and liked what a saw there as well.
You could always consider Tractgard, my personal favorite for inexpensive "maintenance".