It would depend more on the overall geometry of the bike, and how you prefer your setup, as opposed to looking purely at wheel size. Riser bars would give you a more upright position and shift your weight back slightly, whereas flat bars would lower your riding position and shift weight more to the front wheel. You can fiddle further with bar height by flipping your stem, if it is an angled stem. It boils down to personal preference at the end of the day.
