If you are creating a digital book, you don't have to worry about the page count. Otherwise, talk to your printer and compare costs.
If we are talking about a traditional book publisher, they would tend to print in the largest signatures they can. Signature size would mainly be determined by the press size/type and the page size. If you are using a print-on-demand publisher, you might be down to a 2-page count. If you go strictly by a 4-page count, you might end up with a number of 32-page signatures (two 16s stacked), 16 pagers, 8 pagers, and 4 pagers. It might cost as much to run and 8 and 4 together (12 total) as it would a 16 pager (make ready vs paper costs).