I am certain that his question has come up before, but I know that lots of people make changes to their favorite daily pen --according to mood, etc.
My favorite "war horse" pen is an older (1980s?) tortoise-shell Pelikan with a fine point nib that has been worn a bit to a slightly sharper edge. Take a look.
So, what is YOUR war horse pen? The one you want to put your new favorite ink in?