Plumbing the tank for a sump and using the amazon river as the sump... with many small low flow powerheads to prevent waste from collecting on the bottom...
Ignore than answer, "the best" is simply not realistic
STXman;4107736; said:
and what is the least expensive filter but still good for a 75
Two Aqua Clear 110s are what I use to fitler my 75 gal and I'm quite happy with the results. If you have a lot of decor you may wish to add a small powerhead to prevent waste from collecting in/under the decor.
There are a lot of quality filters out there that can be used to filter a 75 gal. In general using two filters is a better approach than one.