For every 10 people that you ask this question, you will get 10 different opinions!

Charlie is right that sand filters are the easiest to maintain. DE filters can filter out the smallest particles. And, though some people love them, cartridge filters can be a hassle to clean and can be expensive to replace. To clean a sand filter, it is simply a matter of turning a handle on the multiport valve a couple of times and you are done. DE filters have to be refilled with DE every time you clean them and some DE filters are a little difficult to reassemble I think. Cartridge filters have to be removed, soaked, sprayed off, etc. and occasionally replaced.

I will tell you that all of the moderators of this forum have sand filters. It may not filter out quite as small of particles as a DE filter can, but at least in my pool, I doubt you would be able to tell. My pool is always very clear. Some of us do add a little DE to our sand filters to help it filter just a little better.

Adding DE to a Sand Filter

Hope this helps.