Usually the couch, but I have used all the designations that you mentioned at one time or another.
I suppose it could also be the potato holder.
i call it a bed when there not enough place to sleep in the house
The big soft chair.
Couch and it must be comfy the dog likes it.
sofa or loveseat (both "couches" in the sense of "NO CLIMBING ON THE COUCH!")
A super sexy couch...
please tell me someone else is thinking of those episode of family guy... leave it on the davenport, the devan, the chifferobe... now i finally know what all of those mean haha!