I've flown both of them, more so the PA28 than the 172.
Even though I fly the PA28 on regular(ish) basis, i'd still prefer the 172 is I could get my mits on it regularly.
I prefer the 172 because it's got more room, can carry more, and it's not as fond of the tarmac stuff. Comparing the 172M and the PA28-151. The PA28 is miles easier to land. But I still like those manual flaps a lot more.