Welcome to the forum, wuuf4u, I hope you find the forum to be a source of useful information for you.
I will give you my opinion on the topics you raise, bearing in mind that some much smarter and more experienced than I may disagree or give you better.
The genre of low-cost ammo sold as practice/target are typically FMJ bullets of rather standardized weights. This category includes Blazer, WWB, S&B, PMC, etc., etc. The FMJ bullet has not been accepted as an effective self-defense round for some time regardless of the manufacturer or the gun being used. The case material is not relevant, the aluminum cases are simply cheaper.
Self-defense rounds are an entirely different category using various designs of the hollow-point bullet, and being offered in different bullet weights. Which bullet weight from which manufacturer for what barrel length is an discussion which is largely unnecessary for practice ammo.
Someone said buy what you can find for practice. I don't disagree with that, it just happens that I find Blazer cleaner and somewhat more accurate than most if I have my choice.
What ammo to buy for self defense in a particular gun is a forum question that would likely get you a bunch of responses.