So... I work with Reefapalooza, so consider the source.
That said, I go to all the RAP's and also go to MACNA.
My basic description of the two are this. RAP is more "end user" aimed, and MACNA is more Vendor aimed. Now that's not 100% true in either case, but to me the biggest differences are that MACNA has a TON of speakers, a couple real fun parties with the full conference pass, and less crowds. MACNA does indeed have coral sellers, but not nearly the volume that RAP has. Both have major manufacturers to chat up and ask questions of their products. RAP is cheaper to get in the door, lots of people pouring over the latest, and not so latest coral eye candy. RAP also has speakers and IMO a bigger raffle, but MACNA also definitely has raffles daily.
No reason not to go to both if you have the time and means. Both different, but both also good.