I generally use standard Bicycle rider backs as a baseline for decks produced by bicycle and most custom decks, and standard Bee decks for those with casino stock. Lots of things determine handling. The biggest ones for me in terms of finish are static and dynamic friction. Static friction is the deck's willingness to hold together in packs. This is good for flourishes, cuts, and the like. Dynamic friction determines how well a deck spreads or fans. You need to find a good balance between the two. For example: If you have a deck that clumps crazy bad, but stays together in flourishes, it doesn't have enough dynamic friction. Bad handling. If you have a deck that fans beautifully but just can't hold on to them, it needs more static friction. Bad handling.
The stock preference differs drastically from person to person. Some people like stiff, some like it soft, thin, thick, it's all personal preference. What makes a BAD stock, is if it's noodly. No matter what stock type, you want it to snap back into place quickly. Aside from that, just use your overall judgment on what the deck feels like.