I would spend the extra money only if it makes you more comfy in the cockpit. Just like in AH, once you get the basics of flying down, you can manage to fly just about anything and fly it well once you learn that ACs particlar characteristics/operating procedures. The size of the trainer is not that important.
The 150/152 is a fun little plane to fly, especially solo. Things will happen a little slower in the 150/152 than the other planes, which is a good thing while learning.
The 172 feels a bit more ponderous...it has a good bit more wing to roll. Control inputs are not as crisp and take a bit more arm. Flying a 172 in turbulance can give you a real arm work-out. But it is much much more comfy than the 150/152 with two grown men side by side.
I prefer high wing for training personally due to better visibility, but the Piper is on par with the 172. Landing takes a bit more getting used to with the Piper due to ground effect of the low wing config.