We love both Rainforest Cafe and Earl of Sandwich, and we eat at both on our family trips, but they are very different restaurants. If you are trying to decide between the two, it depends on what you are looking for in a meal.
Rainforest Cafe has great theming, and it's a lot of fun. My sons insist on eating there every trip. We've tried several different dishes, and we've enjoyed everything we've had there. DH and I usually split a meal because the portions are huge. As a side note, I think they have the best veggie burger in WDW. The prices are a bit high though.
Earl of Sandwich has absolutely delicious sandwiches, and the prices are great, especially by WDW standards. The line is usually very long, but don't let that scare you away - it moves much more quickly than it looks like it would.