Of the ones you mention (I'm familiar with them all except Spindrift) I'd opt for Trends Beachfront. It coundn't be any more convenient, right at the main pier on the front side where you get off the water taxi, next to the Sandbox restaurant. Fairly new, lovely green and pink, nice simple rooms. Think they're around US$30 double. Often it's full, due to its handy location.
The Seaside Cabanas across the way from there also are convenient and nice, with a bit more space than Trends.
--Lan Sluder
Belize First Magazine
http://www.turq.com/belizefirst/