In real broad terms:
1) The heavier the bullet, the more it resists being torn apart and deflected by barriers (all else being equal, a cheap target 147 gr won't be better than a well constructed bonded 124 gr). Retained mass is good.
2) +P is faster, as you noted. It may be faster, that doesn't mean it's better. You will find +P in 124 gr and 135 gr that pass the FBI tests. It's primarily a way to get the lighter bullets through the barriers. +P+ is marketing, there is no SAAMI spec for such a thing. It may or may not actually be faster than +P. You can overdrive a bullet, causing it to fragment or open too fast, reducing penetration. Once again, retained mass is good. This is a rookie mistake, getting caught up in the "energy" stats or thinking that if a bullet at 950 fps is good, 1150 fps must be better. It isn't. Keeping the bullet in the brackets it was designed to expand without fragmenting in is best.
3) Don't over think it. DocGKR publishes information on FBI testing. Find a cartridge on his list that your gun likes, that's available in reasonable quantities, and forget about it.
https://pistol-forum.com/showthread....y-load-testing shows three good 147 gr offerings and the results of bare gel, 4 layer denim, and auto glass. Auto glass tends to also show how a bullet does against bone, as it turns out.