The racors will trap water and allow you to drain it as well. You can
also fit one with an alarm sensor. If you haven't been having problems
with water, i'd just stick with one of those. Look at the cost of the
replacement elements to decide between a spin-on and a cartridge. I
have both in my fuel stream. Racor 900's as primaries, and I replaced
that dual CAV cartridge setup on the engine with a Racor spin-on. The
cartridges are much cheaper and easier to replace. The spin on
requires draining then removal, then a special wrench that grabs the
plastic bottom bowl along with a filter wrench to separate it from the
spin-on element. Harder to change and more expensive, but I only
change it once a year, since pretty much nothing ever makes it past
the Racor primary (2 micron cartridges).