F350: 4.30 or 3.73 Gears

I really hate to enter in to this spirited conversation mid stream , but I am in desperate need of advice. I HAD a 2013 F-350 6.7psd 3.73 rear that towed my 15000# fifth wheel. It has been wrecked and now I am looking @ a 2016 F-350 or F-450 . My question is if I opt for 4.30 gears what will I gain /sacrifice over my 2013 in terms of fuel milage, top end etc.etc. I understand that I will have a better bottom end but at which cost.

I would greatly appreciate any advice or feed back that can be offered