Agree with Julian Storey, either's a good solid training/GA aircraft, I've flown both (>120 hrs on PA28's) and there are advantages/disadvantages to both as well as personal likes/dislikes. Neither is fancy/sexy/clever nor tries to be which is a good thing as far as I'm concerned.
To be honest though, it doesn't really matter what you train in, your choice is going to be limited anyway, C150/152/172, PA28 (various types Cadet/Cherokee etc), Robin (various) or maybe a DA20 Diamond (poss. more expensive??).
It's a bit like being over-fussy about the make of small hatchback you learn to drive in. The only exception would be dependent on your height, if you're much over 5'10" a C150/152 will be a bit cramped legroom-wise, (I know, I trained in a C150 and am 6'1"!!) but the C172 is fine in that respect.
If I was doing it again, I'd try several different aircraft and choose the one I felt most comfortable with in conjuction with being happy with the school and instructors (& of course, price).
Whatever you choose, have fun and good luck.