I'm torn between 2, 3 and 4 but I'll have to go with the printed Grassington sofa as It's so unique!

If you both like to lie on the sofa then definitely go for a corner or a corner-chaise. It may not look as open/spacious, but you've got to strike the balance between looks and how you like to live. If you can't enjoy relaxing on the sofa then it defeats the point as you just won't use it. We had an amazingly comfy corner sofa which we (and our guests) loved but we had to change it to a 3 seater when we moved house and it just wasn't right for our room. I miss it so much and next time we buy a sofa I will absolutely be buying a corner or a corner-chaise. We like to lie on the sofa too and the 3 seater that we have is way too cramped.

I think you could go various ways. I like the rug, can it go under the sofa feet? (Hard to tell how wide it is from the photo). The art seems a bit small, it often works better if it's hung just a few inches over the sofa to connect with it. I'm not sure if this art is big enough though as 4 seater sofa sizes vary. I'd probably repeat the brass for a coffee table or floor lamp and then I've picked up colours in the art for cushions but maybe vary the texture with linen etc rather than just all velvet. I think it will look great once furnished and accessorised 😊

Is your chesterfield a dark colour? Either of the second two would lighten the whole look. You could get another plainer chesterfield style in linen to contrast with the leather. Consider slip covers if you chose cream, maybe a pale grey would be more foregiving and match your silvery wallpaper.