I assume you're looking at brand new tow vehicles, not used. From what I read, I think Ford appears to have overcome their issues with the EcoBoost. Earlier vehicles had problems with them.
I know folks have had good luck with their F150 Eco. They appear to have amazing tow/cargo capacity. I almost went down that path, but instead opted for a GMC Sierra half ton. Just didn't want to deal with potential issues with the Eco Boost.
All things considered, and assuming the prices are roughly or reasonably close, I personally would opt for the 3/4 ton. I say that even with me owning a 1/2 ton today. I think the diesel will have a better resale value with over 100K miles than a V6.. turbocharged, or not.
Mike