I haven't driven a Cayman R, or a 987 Spyder. Or a Cayman GT4. Or a 981.
Given that huge bank of knowledge, I'm glad I got the 987.2S. I really strongly considered the Spyder, but the lack of a real top scared me off. For how we've used this car, including a number of long weekend trips, I think the Spyder would have been an annoyance and I'm glad I didn't go for it.
I think now and then that I might be happier with a Cayman S, as the little convertible annoyances (squeaks and rattles mostly) do bother me. And more often than not, it's simply too hot and humid here for me to be comfortable driving with the top down. But in the spring and fall, it's really pretty nice having a convertible.