I've stayed at the SunBreeze and have toured Tropica a couple of times.
SunBreeze has the edge on location (it's right at the edge of town, within walking distance of everything) and management (GM Julia Edwards is a doll). Rooms are large but somewhat motel-like.
Tropica is about 1 1/2 miles from town. The beach is a plus, one of the best on the island. The rooms are on the smallish side.
Both have pools and (rather pricey) restaurants on site.
They're both good places, but depending on the deal you get, I'd give the edge to SunBreeze.
Fodor's & Belize First