Both dresses are super cute, so I can see why you're having difficulty deciding. However, the second dress might be better for you. It has a bit more room in the bust area, and the longer length would be more flattering on a taller frame.
That being said, if you love the first dress and feel confident in it, you should go for it! Or if you want another option - plenty of white party dresses here. I hope you like it!