I cant really say that either is better, having used neither one. What I can tell you is that fluval has never let me down. I have both a 305 and 405 and have had no issues at all with either. I've got a few friends who have fx5's on their tanks and love them. I can also tell you that the fx5 pumps almost twice as much water as the marinland (925gph vs 530gph).
IMO, the c-530 would be pushing it on your tank. Even though the fx5 is a little more expensive, I'd go for it just because you're getting almost twice the filter for not much more.