Still air or forced air?? Why not both??

So after tweaking a friend's old home made incubator, I decided to make my own. I was just on the fence whether I wanted a still air incubator or a forced air incubator....so I made 2!!! My smaller one (Mark 1) has a 15 watt bulb on a dimmer and a 12v fan to circulate the air. My larger one (Mark 2) also has a dimmer but uses a 25 watt bulb. So far the dimmer and low wattage bulbs seem to work best for keeping the temp at a constant 99. I'll be getting some eggs by Monday (fingers crossed) and we can put these to the test. Six eggs will be going into each of them and let's see who hatches the most chicks. Bets anyone?