I read and watched reviews, lurked on a few of the coffee forums to see the consensus on what sort of coffee the different options would make. From there it was a simple step for me to pick the highest clarity burrs I could get as I really love my ZP6 for pour overs and I had grown to dislike the body focused espresso my Zero made.
I wouldn’t spend the sort of money the SSP burrs are, be they 64s or 83s, unless you either want to try and then sell them, or you are very sure you know what you want.
If you don’t know what you want based on what you have now (even if its I don’t want what I have now like me) then if you really really lucky you might have coffee meet ups near by that you can try different grinders, otherwise you are at the mercy of what grinders the specialist coffee shops have near you for taste testing.