I'm really picky on couches. They need to be the right proportions otherwise my back starts to ache sitting on them too long, and I'm the type who wants to snuggle and wedge myself into the corner with a good book. So many couches are the wrong angle, too long on the butt cushion so you end up hunching, not supportive enough, etc.
The first couch that I LOVED and was so comfortable we got at Goodwill on a random day for $20. We were juniors in college and had that couch for two years. When we graduated we didn't have room to bring it home with us (university was 6 hours away), so we ended up selling it for $40 to another deserving poor college kid.
Then DH and I cycled through a few IKEA futons (too long on the seat and you end up hunching/bad for the lower back), a few freebie couches from family (lost all support and too sink-y), a few craiglist couches (better, but after more than an hour sitting on them both our backs start aching).
Eventually we gave up on the second-hand couches because we actively avoided sitting on them and were having no luck scouring goodwill/facebook swaps/craigslist. The search was just getting exhausting and we went un-mustachian and decided to go to a real store.
Found a faux leather couch from Schniedermans that I liked a lot for a while (paid $2k ouch!), but the stuffing quickly lost its supportiveness and we ran into the same problem. We also began disliking how we "stuck" to the couch on summer days wearing shorts, but we did like how easy it was to clean. Sold that one on craigslist and went back to our old slouchy IKEA futon while we looked for something else.
Finally, we bit the bullet and bought another, higher quality couch from Schniedermans again, I think. It was the same brand as the original awesome college couch - a Bluesteel couch. Much more supportive, proper proportions, and I can snuggle up on it for hours with my hoard of library books. We did pay I think almost $4k for it which I feel is outrageous for a couch, but I finally like sitting down on a couch again so I feel like it was worth it. I suffered through 3+ years of uncomfortable couches and I've finally accepted that I'm willing to pay a bit more to not have my back ache :) Of course, I wish we could have struck gold at goodwill like we did in college, but the stars were not aligning.
This one is fabric, so a bit more comfortable on the skin than the faux leather, and we purposely chose very durable fabric because we will have kids at some point. Our plan is to invest in a sheet or spring for a couch cover for the younger years to prevent most of the bigger stains, and possibly invest in a kid-friendly, crappy couch for the family room and hide this nice one somewhere else where kids are less likely to get at it. That's what my own parents did, we had this hideous brown plaid couch in the family room for about 9 or 10 years and the nice couch downstairs where we spent less time. Then when we got older we switched and the crappy couch got put downstairs for kids to hang out on and the nice couch up in the public family room.