There’s an algorithm I always use:
Take the average of how much Torah you already know, plus how much you intend to still learn, plus how much time and effort you know you will commit to Torah study. Then multiply that by the square root of your age minus the amount of best friends you have. That should give you your result.
Seriously. get what you think will be useful. I, personally, prefer the mini sets, I’m often on the go. It allows me to learn instantly on the go.