I voted for Back At The Funny Farm because I saw them open with it at Leicester De Montfort Hall on the Another Perfect Day tour in 1983 and it was electrifying! They were using insane amounts of dry ice at that gig and the combination of a 'coffin' stage prop opening, bathed in bright white light and gulping down mouthfuls of dry ice as opposed to the normal oxygen - and suddenly becoming aware of Lemmy barking this tune about two feet from my face, was mind-blowing! it makes me break out in goose-bumps just thinking about it.
It could easily have been Iron Fist, Bomber or Dr Rock though. All of those songs touch a nerve as set-openers for me for different reasons but all concert-related. Note that all of these numbers are lyrically very strong and contain potent imagery. This is not to say that the other tunes don't but, on a personal level, these tunes all act as markers for a misspent youth for me!
Could not agree more same here desertrat, remember that gig and to hear Back at the funny farm then was a wise choice. It is a great set opener to be honest, and a lot of people seem to overlook it, but its still is a great song all the same.
Sometimes wonder Motorhead have so many great songs to choose from as a set opener they are spoilt for choice in what they must choose.