for training I would recommend C150, it's more forgiving, slower, therefore easier to navigate and it gives you a bit more time to actually understand what the instructor is trying to tell you. I never bounced a C150 during my training, it basically lands itself. Stall recoveries are easy too, and should your examiner pull your throttle back to simulate and engine failure whilst you're doing the overhead join, you can pretty much pull your flaps out and go as tight as you can and you'll make it.. Try that in a pa28 and if you're speed is not right you will float forever. C150 allows you to learn basics very quickly, however, as soon as that licence is sorted, I would pick pa28 over c150 at any day of the week. As for training the only exercise where pa28 is in some way easier to handle is steep turns - I found it more stable and easier to maintain constant bank angle than c150
I generally believe that when it comes to quality training, one shouldn't look for the easy way out as hardship builds skill and character.. however when the price for a lesson is set where it is, you are probably better off knocking that training in a relatively shorter way and leaving some budget for staying current post licence than struggling with a more slippery plane and blowing all your flying budget for a year