IPhone 5 or Galaxy S4?

I'm going to be getting a new phone soon and I'm not sure which one I should pick. I am on the T-Mobile carrier if that helps. Basically though would the Galaxy S4 be worth the extra $50 or should I just save my money and get the iPhone 5. Right now I have an android made by Samsung but have been wanting an iPhone since they first came out. Thank you for your help.