Buying advice? 2012 Ram 3500HO vs 2013 Ram 2500 Longhorn vs 2015 Ram 2500 Longhorn

Hi there, I‘m looking to update our current 99 2500 manual for a more luxurious truck to pull our 5th wheel. The 5th wheel is an 11,000lb gvwr grand design reflection. Option #1- 2012 3500 HO La...