I’ve had both, an original 1987 MK4 AC and several plus 8s. The Cobra was ace to look at and was ok to drive but it really was a dry weather car only and the weather equipment was awful and fiddly to fit. I did drive to Switzerland in it and that was great fun.
Whilst pretty archaic, it was still better to drive than any of my Morgans. BUT, I’d have a plus 8 for touring over the Cobra any day. Factor in the car you’re looking at is a kit car and really the Plus 8 is the winner. Go and see both and test drive them.