fly the 172 and 28 with about equal regularity. All advice Backpacker gives is good but from an actual flying point of view there's not much difference apart from the fact it might float a bit more on the flare than the 172 if you come in a couple of knots too fast. The biggest difference is they smell different inside.
I fly both, but prefer the Piper because I get the feeling that when Cessna designed the 172, they finished the design and said: whoops, we need a seat for the pilot to sit so bunged in a foldaway stool. Then they decided they needed a place to put instruments and fitted a sheet of plywood to screw them in. The Archer III, with it's overhead switches and lack of ignition key, actually gives me the feeling that I am starting a REAL plane - I remember the time I took a friend up in a 172 and he asked me - do ALL planes need a key to start them, even an Airbus 380???
But seriously, I prefer the Piper, ground effect usually helps a smoother landing but as previously said, coming in hot can mean a longer flare......