Aiding the Maillard reaction: Baking Powder or Baking Soda?
You want to use baking soda. Baking powder is used as a leavening agent and does this by combining an acid and a base, so it would not make your chicken more alkaline. Baking soda, on the other hand is just sodium bicarbonate and will make your chicken more alkaline.

However, baking soda, especially if used in excessive amounts, will give your chicken a bad taste. Baking soda tastes bitter, and cooking it for too long at high heat exacerbates that.

From reading online, it seems that adding baking soda will indeed make your chicken look much browner (the same way that pretzels are dipped in lye to produce their brown colour), but it would affect the texture/taste of your chicken. 

If you want to add more flavour, I would think that properly browning the chicken (using high heat, having patience) would be more effective than adding baking soda, which might give the appearance, but not the taste.