I would follow the procedure as layed down in the QRH.
For my type that says
Descend to 10'000 or MEA.
Because of this we would have to divert.
As I would have been keeping track of wx and availability of en-route divs throughout the flight there would be no need for desicion making as to where to go.
The type of descent would depend on where I was ref nat tracks.
The procedures for initial descent out of NAT airspace are well documented.
Once under the tracks and pointing in the right direction I would look again at the fuel required and wx and either cruise descend with protable O2 near by or get down early to the MID teens and then cruise descend from there.