The Q&A is simply this:
1) Do you like a stiff, firm, or floppy putter?
2) Do you like a grippy or smooth putter?
3) Do you like overstable or understable putters?
4) Do you like Beads or no Beads?
5) Do you like Shallow, deep, or in between rims on putters?
6) Do you like premium plastic or baseline plastic?
Now number 6 is tricky because premium plastic in putters isn't often a good idea but there are some people who use Crystal Challengers, Gold Line Pure's, and other such top end putters. It is often advised that baseline (DX, Pro D, KC, JK, Zero, M, S, SS, SSS, and such are used).
The questions can also be easily answered if you know your putting style (spin or push) as most spin putters like understable, soft, grippy putters and most push putters like firm, beaded, stable to overstable putters.
The process to figuring this all out by trial and error involves buying some discs that represent the categories. I can explain this more later for you but for now.