Allen vs Lamar hopefully will be a rivalry to last for years... but how will Lamar's game translate over the long haul. How many years can he run like he does and if/when he slows down how effective will he be. Josh is a passer, he can run but his run game is complimentary. He could play for 10+ years--even if he loses some arm strength it should still be way above average.
I much prefer Allen over Lamar.