I went with a 16 tooth front, I really like it alot.
The 16 tooth front sprocket is better for launches and midrange. Also, you can use the stock chain, and because you're going to a smaller sprocket, you actually increase your wheelbase SLIGHTLY which helps keep your front wheel down. (the difference is maybe 1/8").
I love the 16 tooth front sprocket. It costs me about $30 installed, and the bike pulls much harder out of the hole, I need less clutch when riding with my wife, and I love the low and mid range improvement.
16 tooth has my vote!
Mike