There are a few considerations for choosing an above counter basin. The main concern is whether you will be mounting your tap on the basin itself or the vanity benchtop; does the basin need a taphole or not. If so, how many? If your tap is a mixer, you will only need one taphole. On the other hand, if you opt for a traditional set, a tap and hot and cold turn assemblies, it will need three tap holes.
Other considerations relate to size and style, which is a personal preference.