Slight problem at the moment is that Ilford liquid developers are mostly out of stock (but allegedly starting to arrive - check with Silverprint - if anyone has some, they will) and powdered developers are extinct (at the time of writing).

I would just repeat what others have said: FP4+ in a developer that comes as a liquid (for simplicity's sake). If you have trouble finding DDX, have a look at Rodinal. It has a shelflife in an opened bottle that exceeds the lifetime of the known universe, it has good graduation and sharpness and it's legendary grain is not an issue in 4x5...

Have fun. Bob.