Camping in a field in Hainault Forest Country Park, 3 days / 2 nights next week.
Literally just sleeping inside it, out of the two I just posted, the 2 man has the groundsheeted "porch", but the 3 man doesn't.
I would always go for the extra space.
If you are going to do more than one trip, you would get a lot more for an extra £20.