After looking at a lot of sofas and not liking the quality of many, we opted for re-upholstering our old one. It cost about the same price as a good quality new one, it was an expensive to buy in the first place but has lasted. To buy a similar one from the same company was about 50% dearer than the upholstery.
I think the problem is that you will always find someone who has had a problem with any given national company such as Harvey, DFS etc. Perhaps it's safer to buy a well-known brand, Ercol, Parker-Knoll etc, and then you've always got the manufacturer to fall back on if there's a problem the dealer is being awkward about.
There is family owned furniture shop near me that ONLY sells what they have in stock in the showrooms. This means that you can see the actual sofa/furniture you are buying and get it delivered the same day.They have an excellent reputation and have been trading from the same shops for over 50 years. Prices are slightly more than the big names but customers prefer them. They started with 1 shop and now have 6 all in the same street.
Thank you for all the replies so far.
As regards budget we are looking at spending a maximum of £3000 and we need at least 4 seats. I am thinking about 2 of these for instance.
I have just ordered two new sofas from http://www.sofasofa.co.uk. My previous ones came from there too and I have just replaced them after 17 years! Really good sofas.
Their stuff won't last as long, at least I don't think it will, but there is an element of "how good does it need to be" - an interesting price/quality equation.