OK. So, I will now put my Salesmans hat on. 35 years of selling these bloody things would of had a rub off!.
Number 1. It is not all about the fabric/style/look, it is about the COMFORT. You are the one that is going to be sitting in this thing for 'hopefully' an evening =4 hours a day, whatever it is made from it NEEDS to be COMFORTABLE!
Number 2. You NEED to go into a store and try out these things, (Agree with Ian, a family retailer would normally give you above and beyond service. Take a book, sit in the sofa and wriggle about for 30 mins, just like a bed purchase, you DO NOT GO UP TO IT AND PRESS THE EDGE AND SAY 'THAT SEEMS FIRM ENOUGH!' You need to test it.
Number 3. Interogate the Salesman. Ask about the frame manufacture, what wood is used, what options of interior fillings, if he cannot answer you walk away, they are not worth their salt.
Number 4. The Salesman should be ASKING YOU what the sofas are going to be used for, Family use, kids, pets, etc. etc. Your choice of colours fabrics come into it now, and he/she can advise. Pigmented Leather good for family use, Aniline for more luxury /cosmetic scene. Advise on Protection situations treatments etc. Ask for a sample and do a few tests of your own.
Number 4. Interest Free credit is paid for somewhere, mostly within your suite! If its a named brand you can price compare. Be wary of chinese imports.