A good quality sofa and whats under the fabric should last much longer than 5 years. Better brand sofas will say they have a lifetime warranty on the structure, this includes any sagging of the seat. The seat is whats under the cushions your sitting on.
The seat cushions should have a high density HR foam 2.0 to 2.5, higher the number the longer the foam will holdup.
Go online to the manufacturers website and see how easily it is to contact them about their products and warranties. If all you get is a dealer locator then I would shy away from that manufacturer. Any and all issues you will have will be up at the retailer and not all dealers/ retailers provide the same level of service. The problem is, most of the time you dont know about this until after the sale. A good dealer will have a very flexible return policy and your satisfaction is a higher priority to them.

Also, I encourage anyone who has a sofa, even if its older than 5 years and having issues is to call up with the retailer and manufacturer to address any issues with them.

Any manufacturer that knows they are building the best quality sofa, will stand behind their product, and this includes customer service at the manufacturers level.

I found out the hard way that not all manufacturers offering 8-way have a decent product. I bought a King Hickory and the fabric sample looked gorgeous. Guess that's where they skimped because after a month the sofa looked 20 years old. We have no children, dogs, etc. It's trash.

I am also looking at sofas and from this website I learned of several manufacturers which I hope to check out this weekend....C R Laine and Smith Brothers of Berne. I was working with a designer and she recommended Parker Southern and although this site gives very mixed reviews of Ethan Allen, she said they were decent. The frustrating thing is some of the stores that carry these brands (except Ethan Allen) are small and will only have maybe 1 or 2 models in their showroom. Or sometimes you have to go to a large design center with a designer--not very convenient.

This is one reason in my 1st post: "whats under the fabric" and the fabric is the single most important factor when considering all other factors in purchasing upholstery. You should try and separate the emotional aspect of a beautiful fabric and decide just how practical this fabric is. Other choices such as pillows and accents that allows for fabrics that maynot be the most durable.

I sell a lot of furniture lines and I am really impressed with the quality of CR Laine and TCS (both are designer brands and are higher end than the others you are mentioning). Ethan Allan is also in this group but is not as good.

In the lower priced market I think Bassett is a standout for quality/price). I would choose Bassett. (Smith Brothers of Berne, Parker Southern, King Hickory are in this lower group).

Before buying a sofa, spend some time to read about some sofa buying basics. The sofa you buy should be chosen based on these factors.