i would definately say the remora or remora pro,
for the size and money idont think there is a better hang on skimmer.
plus it will out produce any other hang on skimmer you can buy.
if you want to go a little cheaper and not quite as good the coralife hang on needle wheel skimmers are suppose to be good, much better than prism, berlin, sea clown, bakpack.
dont skimp on the skimmer!!! probably the singular most important piece of equipment you own!!
also, if you have a pound per gallon of live rock i would suggest removing the media from your canister filter and just runing carbon in it.
so go out and buy that remora pro!!! i see used ones on ebay often!