You can get good results with either I imagine...as long as it is being used as 'active' filtration (water is forced to go through) and not 'passive' (water goes around it - like a bag placed in a sump's water column).
I personally use a 100 micron filter pad over a drip plate with a 2nd micron pad that is sandwiched with carbon in between, so the water is forced throughthe carbon; thus getting better performance and results. I change out carbon every week when pad is dirty/plugged with detritus. I have about a 100-110gal of total water volume (minus rocks, sand, etc.). Per Randy's/Boomer's guideline of 1 cup of carbon per 100 gal volume used per month; I split into 1/4-1/3 cup per week. This has worked VERY WELL for my set up.