www.metro.co.uk/2013/11/13/jubilee-line-named-favourite-tube-line-northern-line-least-4185453/

A survey has been carried out amongst London commuters regarding their favourite and least favourite underground lines.

Favourite Tube lines:
1 Jubilee 24 per cent
2 Victoria 19 per cent
3 Central 12 per cent
4 Piccadilly 12 per cent
5 Metropolitan eight per cent
6 District seven per cent
7 Northern seven per cent
8 Bakerloo three per cent
9 Hammersmith & City three per cent
10 Circle two per cent
11 Waterloo & City two per cent

Least favourite:
1 Northern 20 per cent
2 District seven per cent
3 Bakerloo six per cent
4 Circle five per cent
5 Central four per cent
6 Hammersmith & City four per cent
7 Metropolitan three per cent
8 Waterloo & City three per cent
9 Jubilee two per cent
10 Piccadilly two per cent
11 Victoria one per cent

The Northern line is one I have used the most (both sides of it).
I have been on the Piccadily line, Jubilee line and also Victoria line (farely restricted trips when I am down there).

I must admit to preferring the Victoria line and getting off/on at Vauxhall (when that side of London) to get to Kings Cross during rush hour as it doesn't really hit the busy spots the Northern line does.