Neverfull and belt hands down!
First of all the Neverfull is just THE bag, it will be, as MatAllston said, used all year round, when the Tahitiennes just won't.
And the belt is pretty amazing as well, specially if you already have a bag to go with it!
I would say get the rose/pink color right now since it will be a long time before the sand color becomes available. I was lucky, I got mine in sand color yesterday; only being on the wait list for about 1 week before I got mine. I do like the Neverfull MM as well though, I own a Neverfull PM, but it can only hold so much. I would love to get a Salaya for myself, but have to wait since I have already got me a Tahitiennes.....