Upload & Sell: Off
As a photographer, I see no current piece(s) of Canon equipment that will significantly increase my shooting opportunities or image quality, as the only things I see further vaule in for my use is more resolution and low ISO dynamic range. I do expect new cameras to be announced next year that will be interesting. For the amount of money there is no digital medium format camera system either that can be had, so the Canon brand is not really limiting.
As a lens collector, there are numerous items that are missing from my collection. To make things simple, I would choose the 800 5.6 L IS.