While the D7100 front and bottom are plastic, the top and rear are magnesium alloy. And it is dust and water sealed to D800 levels. It is actually a very durable camera. And other than the 4 fps slower and smaller buffer, it is as full featured as the 7DmkII. I wish it had CF support, but dual SD cards work. In fact, for most photographers considering these 2 cameras, the D7100 is by far a better value. In fact, it is probably one of the best values in the DSLR market right now.
My God, you're predictable

How does a discussion about the innovations of the 7D II vs. the 5D Mk III s get turned into a sales pitch for the plasticky Nikon D7100?
Why don't you just say, "I want everyone on earth to buy Nikon," in every post you make? It would save you time.
I made my observations about the 7D Mk II vs the 5D Mk IIIs and am not interested in discussing Nikon. Most Nikonians agree the D7100 is a letdown and what they really wanted was a D400, not a toy.
The 7D Mk II is a revolutionary camera for its class, with 1Dx like features in a sub-$2000 camera. If it had a Sony sensor and 4K video it would be perfection.
The 5Ds is no such animal. It offers nothing really exemplary, except 50mpx, but not on as good a sensor as can be made ... and then, instead of being a good value, it's more expensive.
May have to consider a Sony with an adapter. They're the best bet for coming out with a high-end sensor + 4K video + the compatability with Canon's overall superior lens lineup in the shortest amount of time.
Jack