I have almost always stayed at Banana Beach, which is next door to Mata Rocks. Mata Rocks has a great bar and, as someone mentioned, is near one of the best beaches on the island. I've also stayed at Changes in Lattitude, which was very fun and as a B&B had a completely different feel. Not sure you could beat Renita's breakfasts anywhere on the island. I've also spent one night at Ruby's. I know people like it because it's budget and on the beach, but it is not what I would call clean and I don't think I could stay there for several nights in a row. If budget was the deciding factor for me I'd take Pedro's over Ruby's. This last trip I shared a room with Gela at Conch Shell. It is clean, very simple, very convenient to everything in town, right on the beach and reasonably priced.
That said, Banana Beach is still my favorite because the rooms are good sized, I really like the pools and like being a bit of a distance from town and because they have the best staff anywhere!
Also, I think many have pretty good luck negotiating prices lower than those posted online - especially during low season. Truth is, if you're the right kind of traveller you'll have a good time wherever you stay!