Keep em both. Manning has the resume to push for the #1 spot as the greatest QB to ever play. Luck is one of the most hyped pick since Manning. While it is expected in today's NFL that rookie QB's need to produce immediately, it is always better to have them learn first. The best QB in the NFL today is Rodgers, and he sat behind Favre for 3-4 years. QB's such as Matt Ryan, Joe Flacco, Cam Newton, Andy Dalton, and Sam Bradford have not been consistent enough to judge as being great since their rookie season(s). Keep em both, and hopefully Luck is as good as advertised.