Consider this, you are looking at a 2nd hand Golf
The first one has full main dealer stamps but is in generally poor condition. Its been owned by Shiela from down the road who couldnt give a monkeys about where or even how (kerbing wheels int he process) she parks, whether or not she eats a burger king in the car, whether or not to fling the door open onto a lampost etc etc. BUT yet she has always taken it back to where she bought it for a service (VW main dealer). And the car is sat forsale on the forcourt of such garage.
Kerbed alloys, whilst not pretty - are not the be-all and end all. Afterall, my alloys have been kerbed - but the rest of my car is mechanically perfect!

The second has no main dealer stamps but yet FSH. This car has been owned by a general car lover. He/she has cleaned the car inside and out before your visit (private sale), kept all receipts, was careful never to open the door onto lamposts and watched where they parked to not kerb alloys etc etc.
But this could be worse than your first example! What if those 'FSH' stamps were from Thik-Fit?

Sorry, but no contest with the above.
I know I'd chose the 2nd option everytime.
ETTO.
Lets be realistic, a service, when you get down to the nitty gritty, is just an oil change and oil filter.
No it isn't. There are vital safety checks too. Remind me not to buy a car from you!
And with a main dealer service history, you have traceability, acountability, and general piece of mind (but weather that 'peace of mind' is actually justified - well that is another matter).
I have my Golf serviced by a JCT600 VW garage, it went in just last week. The mechanic who serviced the car is a pal of mine, cost me £80, used long-life VW oil, stamps the book with a JCT600 VW stamp and even puts a bottle of screen wash on the front seat when I collect it (which may or may not of been taken from the service desk
)
I thought JCT600 was a franchised main dealer?

And whooo hooo for a 2 quid bottle of screenwash. I use one of them every week!
I will ask him about this "updating" that people are talking about.
Waiting with interest.

But in all honesty the service you get, even from expensive marque's dealers is often apauling. You are usually talking to the service desk woman/man who has NO IDEA WHATSOEVER about what has just been done to your car. All they have is it written down on a post-it note in amongst a big fat bill with your name on it.
I don't disagree that many main stealers can be appauling - and I don't disagree about the eyecandy on the front desk either. But like I said, you do have some serious back up with using the main stealer - and no independent can give you that depth and level of service.
And sometimes, main dealer servicing can actually save you money. With both Audi and Mercedes, if you use their main dealers for servicing, you automatically get inclusive top level UK and Europe roadside assistance, rescue, and all the other perks which RAC and AA offer. You go to France or Germany, and have any kind of breakdown on their motorways, and if you don't have any 'authorised' breakdown membership, you will be very seriously out of pocket - way more expensive than in the UK (but then a million times more professional too).