Should I choose windows phone 7 or iphone 4?

I’ve been looking at windows phone 7 for a while because of its uniqueness and the zune feature but its not even out after so long,not even in the US,i think apple thinks about the rest of the world more since they announced the launch date of Singapore(my home) the day they announce iphone 4 in the US.
Both phone have pros and cons so can anyone give me a good opinion on which to buy?