To choose the appropriate resolution first select the material, in the below case, PLA. Once PLA is selected, and you click on color, you will then see a list that has colors separated by a label that indicates the resolution. The first entry for black would be the highest resolution, and most expensive, with a layer height or 0.06mm.
I will print in whatever resolution you order...however...it is hugely important that you understand the impact of layer height on how your print will look! Please see this post for pictures of various resolutions. In general the lowest two resolutions should be avoided for anything other than a very basic draft, or in some cases, for a large and simple model.
Finally, I am interested in specialty filaments but have only had an excuse to work with one, that being Colorfab XT which is a carbon fiber reinforced type of filament. If you are interested in some other flavor please let me know as I may want to try it for the experience!