I prefer power filters over UGF for the reason they are easier to clean. Also, I use sand in my tanks, so an UGF or a RUGF will be no good there.
I agree with RTR and Daveddka, it all depends on your personal preference and needs.
I run a canister in my 50 gallon tank, and it works really good. It has gravel in the botttom, but only 1 single 1/2" layer, so I have more space for water
In my 250, I use a wet dry, with an overflow. I have messy fishes (rays) in there, so there was always a flim that formed on top of the water (protein wastes), and I was affraid for my gouramies. Reading some books, I found that overflow systems would take care of the proteous film that was being developed by my pooping machines. (This is common in salwater systems, abd it's solved by the protein skimmer).
So, in my case that's the best system, but that doesn't mean other systems are inferior. Just different.