Settee Idol
If it's between the two of them, my vote would have to be for the futon. Although it's quite lengthy and therefore, less flexible for changing the room layout, it is better for lying or sitting on than the small sofa which sinks (although I haven't actually sat on that one).
It is of course, always handy to have a sofabed for sleepovers to accommodate the waifs and strays in London or friends who can't be bothered to go home.
Metal sides on futons are always a bit uncomfortable, but this could be improved by plenty of cushions to lean against.

Of course you could be rash, get rid of both and start afresh with your ideal choice. Why not have a look round the Boxing Day/New Year Sales for your ideal lounge sofas/chairs etc?
OR Get rid of both & live with cushions & floor space for a little while to experience how much furniture you want to live with!!

Well now that I've thrown a few more ideas into the pot, and created a bit more confusion and indecision, I shall leave you to decide.
Hope you had a good Xmas.
Sharron