WTB complete setup to upgrade from Nikon D7100

Hi everyone, I have someone interested in buying my Sea&Sea Nikon D7100 system, but I would only sell it if I find something better to upgrade to. I'm looking for a complete wide angle setup. I was thinking about a Canon 5DIV or Nikon D850, but I'm not totally sure so I'm also open to suggestions. Preferable items that are located in the USA. 

Thanks!!

I have a Nikon D800, Nauticam housing, 9" glass dome in debatable condition, 6" acrylic etc for sale at a favourable price. You will miss the Tokina 10-17... You can email if you prefer, peteatkinson00@gmail.com

Having left a DX environment for FX with the D800, I'm now back with DX with a D500.

If wide-angle is your priority and you need to travel to dive, I'd really recommend going DX and buying something along D500-based system or Canon equivalent. Wide-angle is SO much easier to achieve with DX and you have to be shooting materials you want to blow up to enormous proportions to see the difference.

As Pete says, there's no Tokina 10-17 equivalent. The Nikkor 16-35 is great but, mercy, you are looking at a 230mm dome which is a horror if you need to travel a lot.

Do you really need a full-frame load of pixels? Nice maybe - but it comes with a lot of downsides for wide angle.