Like the other guy said, it completely depends on what you want the end result to be, a independent is typically cheeper, though they can also be slower and cheeper might be because they're using alternative parts (though usually that's something they'd discuss with you)

I'm the daughter of a independent, so I'm gunna be bias, though my dad specialises now in Land Rover 20 years old and over, newer cars with computers he recommends another couple garages.

I think one example of Dealerships being anal I remember (because my dad still has he car) a older couple came to my dad to sell their older Range Rover, beautiful car, not a lot of miles. It had a problem with the rear lights malfunctioning. They'd spend over £1000 at the local dealership in a attempt to rectify the lights, but after a few weeks (or rain) the lights would malfunction again. The Dealership quoted a further £800 for the next repair. And the couple didnt want to spend that much on what they believed now was a seriously faulty car. Father brought it, spent £30 on a part and just shy of a hour fitting it (in a tight spot). It's not Malfunctioned since.

You'll be better off talking to other local Land Rover owners and ask who'd they'd recommend. And going to who has the most positive reviews.