Steel is stronger, aluminum doesn’t rust.  Resin also doesn’t rust, but it’s not very strong when it’s cold out.  When I was growing up, automobiles bodies only lasted about four years.  Today, ten to fifteen years are not a problem.  That’s because the automobile manufacturers use much better coatings on their steel.  Even so, if you get a scratch that goes down to the bare metal, it will eventually rust through if you don’t put some touch-up paint on it.

It’s the same with pools.  A cheap, poorly-coated steel pool won’t last as long as an expensive, well-coated steel pool.  In any case, if one of the kids scratches the pool down to bare metal, you’ll want to sand and touch-up the spot.  This doesn’t have to be a lot of work – just ten minutes a year to walk around the pool looking for scratches.

If that seems like too much work, try an aluminum pool – no touch-up required!  Since aluminum is an expensive, soft metal, you’ll see a wide price range in aluminum pools.  The thinner, less expensive models bend and dent very easily.  The thicker, stronger models require much more metal, at a much higher price, to be as strong as steel. 

Resin pools are not really resin, anyway.  They always have a metal wall (usually steel) with metal hardware.  Typically, the top rail will be plastic, or the top rail and uprights.

Resin allows for more sweeping lines and curves than metal.  Thick plastic resin is also very heavy, so it adds weight to the pool.  It’s a great look.  The only drawback would seem to be in winter, when the plastic could become brittle.  That just means adjusting how you attach your pool cover – and there are several ways of doing that.  The color may fade or yellow a bit more than paint might, but it’s so gradual that most people would never notice.