Template

Once you add the rider to the dynamics of how a board works (weight distribution), the template is the most important facet of design on the board.

Wide nose:

In general the more parallel the template (wider nose) the more surface area of the rail is exposed during a turn, which means the more resistance created, and the easier it is to turn in one direction. This shape is easier to approach the lip and can hold the board in where there is a lot of power on the wave generating straight speed. The down side to the parallel template is its ability to change directions through carving and the ability to make smooth turning transitions through combinations of moves. This template works best if you ride further forward on the board and like to plane for speed instead of pumping off your rail.

Narrow nose:

A rounder template (narrower nose) exposes less of the rail on any given turn with less hold but allowing for faster transitional turns and basically has a looser feel that is more maneuverable. This template works best if you ride further back on the board and like to pump off of your rail to generate speed.

Channels:

In simple terms channels are basically a part of the board that has a different relation to the water flow creating an area of high pressure lifting the board in that area. The potential down side is channel entry must be smooth or it will create turbulence and slow the board down unnecessarily. Look for a gradual entree where channel starts on the bottom of the board. This will provide the best hold with the least resistance.

Deck channels/Contours:

Have no direct effect on water flow but if designed properly can enhance the geometry of leverage while riding which in turn effects the board's attitude relative to water flow and therefore performance. Proper deck contours can also enhance proper movement of weight distribution over the board.

One of the keys to life,

riding a bodyboard and even selecting a board or board feature, is balance. From my experience you don't want to go too extreme on any of the design traits. As an example for rails you don't want them too flat or too steep, Templates too round or too parallel. Take note, what is proven, what is ridden, and how the best riders ride it.