In this case, both cars are bulletproof. The only thing is that Mazda spare parts, no matter where you are in the world, are an expensive affair compared to any other Japanese company. I experience that every time I go in to get something replaced. Plus, in Pakistan, the MX-5 isn't a very common car, so getting things replaced properly could be a masla- unless you'll do it yourself (which is easy to do in that car as much as I've heard)
I'd say go for the mazda because I'm an MX-5 fan, but Toyota is better in Pakistan... always! 