All things being equal, a 152 is a slightly more capable airplane, and more "modern". (though not much different than the 150M (last model change before the 152)The flying performance gains (if any) are slight.
There are far more differences between early models of the 150 (say 1959-1965) and later models (1966-1977) than there are between the later models of the 150 and the 152's. Having flown numerous examples of both, I would have to say you should choose based on preference for style, and if you want an IFR capable airplane, a 1967 or later model for the larger standard T format panel. Also, the models prior to 1966 have much less luggage room.
I also did all my primary flight training in 172's, and always assumed I could own nothing less. When I started shopping for an airplane, I initially only looked at 172's but couldn't budget for $50K+, so lowered my search to include 152's (assumed at the time that 150's were "lesser" airplanes)
Then I happened to stumble onto a beautiful low time polished 1966 150 (it was on the same webpage as a 152 I was considering) I got a crush on the 150, which blossomed into a full blown love affair once I saw her in person. We've been married now for more than 5 years. I have to say that I'm not really bothered much by the gross weight limitations, nor even with the small cabin. If I have any complaint at all, it's in the lack of horsepower. In my view,the 150-152 really should have come standard with a 125 HP engine. This might just be horsepower itis, based on flights in 150HP upgraded 150's. In a practical way, the 100HP version has continued to be an enjoyable and useful airplane. (I've flown it from California to Oshkosh four times)
