We much prefer Ohana, especially for the price. The Ohana breakfast is yummy (love the sausages!), and we also like the atmosphere at the Poly. We've been there three times, and have had great interaction with Pluto each time.The parade is also fun for little ones.
We've been to Garden Grill once, and wouldn't go back. It was the most expensive meal that we had during our trip last May (about $40 per person for adults) and I felt that the food was just ok - definitely nothing special. We did see Chip, Dale, and Mickey a couple of times each, so that was nice, but Pluto skipped our table entirely! He walked right by once without stopping, and we asked our waitress a couple of times, but he still hadn't made it to our table well after we were done with our meal. Our waitress sent a character handler over after dessert, who said he should be there soon, but he still hadn't come by 15 minutes later, and our toddler was getting tired and restless, so we just left. This doesn't seem to be the norm from the reviews on here, but we were definitely less than thrilled by the experience.