Those are all pretty far from Aquaventure, if you're there to do slides and swimming, and I am fairly sure you'll need to change clothes at least a bit to eat at most of them (the Lagoon Grill might be an exception). Probably throwing on a shirt or cover-up will be OK. We considered Murray's, but after experiencing the size and scope of the place, we decided to stay nearer to Aquaventure. It's a BIIIIIG complex.
We ate at Shark Bites, a sit-down restaurant on the edge of Aquaventure. Most of the other lunch places in the Aquaventure area (Breakwater Grill, Splasher's Snacks, etc.) are walk-up counters with stuff like generic hamburgers and pizza. Shark Bites had conch chowder, cracked conch and some other Bahamas conch specialties, plus the usual kinds of salads and sandwiches. The service was slow (island normal, really), but the food was pretty good. Cave Grill also seemed like a good option, but we didn't have the energy to hike all the way over there and check it out.