BSM all the way, I never understand people's accusation of money grabbing when they aren't even taught by the bigger companies. But firstly, I had 4 instructors before I passed my test: two different independents; one works on his own; and the other is part of a small company. The former was just terrible despite his high ADI grade and I left after 12-15 hours because he was just making me drive in a relatively empty double carriage way to my local town (where the test centre was) and it wasted two-thirds of my time on the way there and back. He was just leeching me of my money) The second instructor taught me for a few lessons and just completely overcomplicated things and I just gave up!
Then when I was at university, I tried BSM as they can arrange for an instructor at home as well. People complain about the relatively long times spent listening to instructors on the side of the road but in my opinion it really helped. The minor issues which I could have gotten from the other instructors weren't tolerated either. The 2 hour lesson system also helped a lot for me personally because I actually could spend a whole hour on just mastering one those bloody manouvers which you would never do again. Also since you tend to book XX hours to get a discount, you can at least change the instructor if you are with a bigger company.
But my advice is if you can get plenty of private practice then a decent independent instructor should be fine. If not, then one of the larger companies.