BJ Penn is on a completely different level than any other fighter in the LW division. It really doesn't matter who wins the Maynard/Edgar fight, because BJ would beat both of those guy easily. Frankie Edgar is a very balanced fighter, good striking ability, good ground game. Maynard is a good wrestler, and thats it. He is like another Sean Sherk, but lacks the same power.
BJ Penn demolishes either one of these fighters, but if I had to pick, I'd go with Frankie Edgar. At least we would see something different. We just saw BJ tool a good wrestler with overrated standup (I used to think Diego had good standup).
On a side not, I want Nick Diaz to come over from SF and fight BJ Penn at a catchweight of 160. If he could fight BJ like he did Gomi at that weight, it could be a hell of a fight.