when is the best time to buy an iphone 3g or blackberry??? advice please?

im trying to decide on an iphone 3g, blackberry curve 8900 or blackberry bold. Which is a better and more reliable phone? Is there another iphone coming out in the summer that will better than the past devices? Will i get a better deal if I get one during the Christmas holiday or wait til my upgrade in july of 2010? can you guys give me some pros and cons to help me choose which phone to get and when to get it:)..its confusing me :/