Modular sectionals are the best when you want to design - this way you can built up whatever couch you need. In a lot of places you can't fit pre-built product and need to play with measurements. Modular designs allow you to do that. Besides, you can always buy an extra piece or un-attach one part and use it somewhere else. That's what modular couches main focus is all about - amazing versatility.
One of best quality full leather chairs from Modway features many great modular sectionals - and of the best series is Commix. They come in true modular nature - you can get pretty much any combination you need. Low-profile, comfy and ultra sleek. Few colors available.
Coaster is company that doesn't need to be introduced, of course. They don't carry too many modular designs, unfortunately, but they DO carry one of the best models around - Hobson. This is true remarkable piece of modular design in light beige fabric. True joy to the eye and to your body.
Moe's very exclusive lineup includes some of the best modular couches around. This particular model doesn't compromise on quality - finished in top grain leather all around. Truly amazing craftsmanship.