As a semi regular user of Mill Hill Broadway it can be a very bleak station, especially in the winter , however I wouldn't nominate it as the bleakest , at least it has a largeish platform canopy , is staffed most of the time and has a station shop on Platform 1 (which is scarcely ever open but that's better then nothing ) , if I were to nominate any station on the south MML it would be Hendon which is just Mill Hill Broadway but with all the afformentioned redeeming qualities removed.
I often wonder what Mill Hill Broadway and Hendon station's looked like Pre M1 , anyone have any photos of that ?
One of the bleakest I've been to is definitely Hawkhead station. A little single platform in a not very nice area of Glasgow right next to a gloomy oil terminal with quite a few rusty neglected sidings nearby. To be honest the whole Paisley Canal branch has a sort of run down bare feel but Hawkhead is definitely the worst of the bunch.