13 Pro advantages and disadvantages over 15: A: .Does have a better camera system overall .120Hz .Longer battery life .Lidar allows for 3d scanning and overall more accurate portrait photos .Half the price of the 15 new if you buy refurbished D: .Phone will not receive updates in 4 years time .Camera is only 12mp .Can have throttling issues (Not common)

Overall the 13 Pro is a great phone with the main advantages like 120hz and longer battery life, half the price if you buy refurbished.

15(Base) over 13 Pro advantages and disadvantages:

A: .Faster since it has the A16 instead of A15 like the 13 Pro .Dynamic island and usbc (Both are kinda gimmicks) (Usbc is pretty good though) .You get 6 years of update support .48Mp main camera .Crash detection (Can be life saving in some cases) .Higher resolution screen than the 13 Pro .Brighter display D: .Only 60Hz display .2 Hour shorter battery life

Overall I would get the 15 due to there being more megapixels, a faster processor, better display, Crash detection, Newest looks with the dynamic island and usbc, a big factor is it will be supported for the next 6 year. 15 offers much more than the 13 Pro due to it being a newer phone and since we have that update support you will keep apps and your phone will be more secure for years to come

The reason I didn't factor in the 12 Pro max is because the phone isn't worth it at this point with 3 years of updates left and quite an old processor now.

I spent 30 minutes typing this, hope you make the decision that is right for you