There are 3 popular types of pool and spa filters. They are D.E., cartridge, and sand filters. All 3 types work well and choosing between them is more a matter of personal preference and prior experience. We carry all types for this reason.
If you don't have a preference then I would go with one of the cartridge filters we stock. They are the least expensive to buy and operate and if you go with a large size (150 sq. ft.) or larger, then maintenance is a snap. The D.E. and sand filters require a backwash valve and in most countries a separation tank.