This is a basic sock arm. Fine. It's classic. But the longer I look at it the more it looks a little cartoonish. This is also skirted sofa but I think it will look better if the skirt started up a little higher; it being so low kind of contributes to the chunkiness of this sofa. This sofa has box cushions (I think that is what it's called). Basically the seat cushions are completely boxed in by the arms. So honestly all in all, this is a very classic, nice looking sofa-- the problem is that I've been looking at sofas for weeks (okay months) so now my taste has become more... refined?
Moving on, here you have a skirted sofa with a rolled (?) arm. This is not a box cushion (see how the ends kind of wrap around. The skirt on this sofa also looks a little short or something to me.
Here's a sofa with an English(?) arm (maybe this is even a saddle arm?). The one accent chair we think we're going to do in this room has a similar arm to it, so I think we're leaning towards a rolled arm for the sofa (don't need to be too matchy-matchy on arms, right?). Something about this particular pictured sofa I really, really like. Maybe it's the mildly contrasted welting. I also like the way the skirt is a bit higher... and even that the back cushions are a little lower and I think the way they are constructed is different. Note this does not have boxed seat cushions though.
Here's another rolled arm sofa (ignore the fabric) which I like though the skirt starts too low and it seems a little.... too upright? or something? I'd want to sit on this one. I don't know the depth measurements on this, but it looks like it might be not deep enough for dear 6'1 husband.