A little English roll arm is a nice touch
or even just one (but only if it has a plump, plush filling).
Perhaps you like a little more padding in the backside? It can be super plush and compact
Just as long as the legs are curvy or bulbous or some shape other than stick-straight or square. That's how I like my couches.
p.s. They should also be in a pleasing, neutral color that allows for plenty of wool blanket and throw pillow switching.