Both are excellent, though for what you want I'd lean toward Victoria House, as it's more accessible for a night out on the town, plus it has a pool, which Mata Chica doesn't.
I've stayed at both and thought the beds were fine at both places, though the "best beds in Belize award" would go to the Inn at Robert's Grove, Turtle Inn, Caye Chapel Island Resort, Cayo Espanto and a few other places.
--Lan Sluder