Interesting thread, the same dilemma I'm going through having just got my PPL in June this year on the 152. The first thing I did post PPL was to get checked out on the PA28 - easier in the circuit esp with that wing out of the way on any turn (not just base to final) and it felt easier to land, prob because of that float. Things I didn't like - trim does not seem to be as good as the Cessna's, manual flaps, one door (SO annoying), seem to hit my knees on the yoke a lot.
Then came a club fly out to Brittany and I still had no takers to fly with me in a PA28 - would have been very expensive and boring on my own! However, the opportunity arose to fly a 172 with another pilot. I got checked out on the 172 and it flew like a dream the 400nm or so to Quiberon.
Likes re 172? Much more satisfying to get trimmed out around the circuit and the cruise. Love those "fire and forget" electrically driven flaps (just look out the window to check though!). TWO doors (yay!), more room in the cockpit. And the trim is right below the throttle which is where you want it on final approach, not on the floor somewhere like the PA28. A few bouncy landings in the 172 during checkout, I suspect because the PA28 had lured me into a false sense of security. Ok that wing's in the way again on any turn. Took the 172 out again today... when you get a good landing out of it, so much more satisfying that a PA28! Did a few circuits in the 172 as well and the landing and take off runs are considerably shorter, according to my random landmarks at Lydd.
Like you ident, there is only one 172 for rent, but two PA28's and a number of PA28 group aircraft as well as the two 152's, which are accessible to 172 pilots with no additional checkout, but of course these are running nearly 24/7 with PPL training!
Decisions, decisions. Right now I like the 172 probably because it feels more familiar, but also because everything in the cockpit seems to be in the right place with minimum fuss. And it has a nice paint job!