Functionally, this one is about if it grips or not when you go one foot (if it doesn't you can always get grip pads, or just get used to it) and about if the snow sticks more or less to the upper part of your snowboard. Resume: if you want your board to grip and to have less snow stuck to it, get a snowboard with a gloss, lacquered top sheet plus some stomp pads.
The top sheet may have a tiny influence in the snowboard flexibility (just like all the other layers, the base and the sidewall do), the top sheet where there is more of a closer-to-be-noticeable-difference will be a natural wood or bambu top sheet. The brands will proudly let you know about this feature, and it's easily noticeable, specially if you are buying on a physical snowboard shop.
Aesthetically a snowboard top sheet has it's influence, the graphics can be printed under the top sheet, on the top sheet itself, or a bit of both to create visual effects. If you'll buy a snowboard at a physical snowboard shop just mind about if the graphics look as well as you want them to. But if you're buying your next snowboard online and are picky about the quality of your graphics - not artistically, not the image itself, but how it look and how defined it is - and also if you really want a board that grips, than keep reading.
How to know if it grips?
Try if you have the chance, ask on a specialized snowboard shop, rent before buying, try on a friends board, if you see the board in the mountains ask the owner if he let's you see if the board grips, its just stepping on it, it's not like you're asking a stranger to take his board for a ride. If that's not possible, just try to spot one an see how glossy (will be more slippery) or how mate (will grip more) is it. Some snowboards come with a grip-lacquer applied zonally (extra grip) where you usually would have a grip pad, these are more distinguishable.
Or forest for the info in the brands site or in the snowboard specifications like a pig looking for truffles. In this case, good luck, and patience, cause you'll need it.
How to know if it grabs more or less snow?
High-gloss lacquered top sheets prevent the snow from sticking.
How to know if it looks good and how it looks?
Just try to see it physically or... go forest again! You shouldn't really worry about this technicalities, all the brands nowadays do a good job in delivering technically amazing graphics with whatever type of material or technique used, And if you must worry about this level of detail than maybe you should do it with performance more than in aesthetics anyway.