I have never had an underground filter, just didn't really like the concept.Plus I hear more negative than positive so I lean towards the popular vote. When I did freshwater I used 2 large HOB
powerfilters I used double what was suggested because I wanted the extra turnover for my african cichlid tank .The only con of a HOB
filter that I can think of is its not appealing to the eye to have it hanging of the back of your tank. Now that switched to saltwater those HOB
filters are with the other pile of stuff I don't need in my garage. With Saltwater if you have enough live rock and decent water flow via powerhead a filter is not really necessary since the live rock acts as a biological filter.