Just got back from a trip to Tufi and the FeBrina. Both were really nice. Tufi had great muck and night dives right off their pier. There was also an incredible amount of life on their outer reefs.
That said, if I had to do it again, I'd just do the FeBrina. Digger is a great dive guide who can find the smallest shrimp and crabs (he's actually the guy that discovered the first pygmy seahorse). You need to be a pretty comfortable diver, though, and be nitrox certified. The bommies were often somewhere around 65 feet at the shallowest and several had a pretty stiff current (even on one night dive!). Dive skills were rewarded, though, by some phenomenal stuff from silver tip sharks down to a half-inch long frog fish.
We visited Walindi at the end of the FeBrina trip and did a dive on their house reef. It was one of the best dives of the trip. Very shallow, OODLES of tiny stuff -- more bulldozer shrimp than you can count, tons of glass shrimp, bunches of stuff. Unfortunately, all of the people on our boat that had stayed at Walindi previously had bad things to say about the operation. In addition, we had heard (and was confirmed) that none of the rooms have air conditioning -- this would have killed us since it was SO hot and humid.
So, for my money, it's FeBrina followed by Tufi followed (a LONG way behind) by Walindi. YMMV.