John's not gonna like me, but I'd go with the D60 or D70 The two reasons is spot metering and more advanced flash which comes in handy for fish photog.
I agree that lenses matter most. Nikon's 60mm f2.8 micro is, IMO, the best macro lenses any one makes.
Can't wait to get my hands on the Nikon D70 that I ordered. Unfortunately, it is backordered at this time. I have been drooling at all of your reef pics for a long time and hope to post some of my own humble photos in the future.