I would personally go with a recommended independent.
Instructors working for a large firm know that no matter how good/bad they are, they will have a queue of people lining up to be taught.
Independents rely mostly on word of mouth, as they do not have a large customer base behind them - if they do a bad job, they won't get paid.
I went with a local independent, and had 15 lessons, including the 2hrs for the test, a couple of my friends went with large companies, and had upwards of 30 hours of lessons.
One failed his test twice with BSM after a total of 35 lessons, then went to my independent, and had a further 8 lessons, was practically re-taught everything, and then passed his next test.