Actually the ignition type has nothing to do with accuracy. Given the right load either will be accurate. Now the flint, if not tuned or primed correctly or you're not used to shooting one does have a slight to long delay where as the percussion is more similar to a center fire rifle. The minor delay, even one ever so slight will cause the shooter to move the sights a tad resulting in "poorer accuracy". But that's the shooter's fault not the rifle's.
Another thing you may want to consider is where you're going to be hunting. Here in PA you can use either flint or percussion (or inline) during the early season but flintlock only during the late season after Christmas. Check your regs.