My 2p worth
I was trained on PA28 and have c150 hours on them. I recently checked out on a C172 Diesel. I loved the 172, being able to look straight down is great and I also found the 172 really easy to fly, it's so forgiving and doesn't even get nasty in a full stall, it's lovely. As Bose X said, all that was required was a trip out of the zone, stalls, steep turns, PFL and back in for flapless, glide and normal approach. My landings weren't as nice as I would like, but I'm sure that I'll sort them out once I've done a few.
To give you an idea of cost difference, Solent School of flying charge £140 for the C172, £145 for a Cherokee 140 and £150 for a warrior (all exc VAT).
If I could only fly 1 type then it would be the PA28 because of the greater load capacity, but I just love the 7 hours endurance, no carb icing, no mixture and great visibility of the C172 diesel.
SW