Hi,
both types are _very_ similar and - imo - VERY good trainers. Both are extremely benign and forgiving.
The C152 always seemed a bit more stable and a bit more powerful with two souls on board. On the other hand it was not as docile as a C150 and the flaps were limited to 30 degrees. The flap preselect was more comfortable than the "free" design of the C150.
The C150 is more docile (if one is allowed to use this words together with the term "Cessna" without being laughed at...) and it was more fun whilst slipping. The 40 degrees flaps are the literal "barn doors". They provide you with interesting glide angles when you have finally learned to flare correctly with them.
I would not say that one type is superior over the other one in terms of training. You'll learn things in the 150 that you won't learn in the 152 and vice versa as it is with every type.
Don't think about it. Go flying! You'll handle other types in the future and you'll be surprised how different a 172 feels to a 152 or a 150...
Have fun :-)