If you've already stayed at both, then don't you already know the good and bad points of both hotels? Some specifics on what info you're looking for would be helpful....
I've stayed at both hotels, too--I stayed at La Ceiba in 2000 and stayed at the Fiesta Sunset Magic Reef Costa Brisas Scape twice this summer. Of the 2 I would stay at the latter again.
La Ceiba was fine back in 2000 when you could still get a room in the "older" section (they're all timeshares now), but the # of cruise ships has increased greatly since then and there is a nice big cruise ship pier parked right in front of La Ceiba's "beach". So not only would you have to put up with the engine noise when those bad boys pull in or leave, but all your pictures would have a big white SHIP in them and the beach loungers would be full of sunburned cruisers in Hawaiian shirts and black socks.
Both hotels are similar, price-wise, but I would give the edge amenity-wise to "Reefscape" (snort) given all the renovations to the premises. You can stay Euro-plan and pay for all meals and drinks. However, staying AI is only slightly more in cost, and that would cover breakfast before diving and all your post-diving drinks and still leave you with plenty of cash for eating dinner in town every night. The staff was friendly, breakfast and lunch were good (I had dinner in town every night), rooms were spotless and the huge pool, hot tub and new beach club were very nice. Plus, the 2 rinse tanks, 2 showers and lockers for dive gear were very convenient.