L5P duramax is at 910 ft lbs now, or maybe 915?
GM and Ford were within 5 ft lbs of each other since 17 in their dick swinging torque contest.
The Cummins is currently leader in torque.
I work at a GM dealer. Would I own any of the 3? Yes, I would.
They are mechanical. They will break.
My Dad went from a 15 with 705ish ft lbs to the 17. It tows better, but drinks more fuel and more def. Probably 16k loaded? 5th wheel.
Ford actually bought the design of their new heads with no exhaust manifolds from GM.
I also have yet to find anything my 13 LML at 705 ft lbs wont move.
20 years ago, a guy was lucky to have 350 ft lbs and was happy as a pig in chit towing with it over a gasser.
My opinion, the Allison is stil the best trans, but the others are gaining finally.
But what you like, they all get the job done.