The launch of the iPhone 5 is just a few days away. We'll find out if this is really on par, if not better than the touted dual-core smartphones that are currently out in the market. In the meantime, I think we can consider the Samsung Galaxy S2 and HTC Sensation. I am personally using the former phone. I love it. I use it as my super mini-tablet because it's blazing fast.
I want to suggest you Samsung Galaxy s2, but before buy s2 if possible just wait for few days, the iPhone 4S was unveiled at Apple's Let's Talk iPhone event on October 4, 2011 in Cupertino, California. Apple started taking pre-orders for the iPhone 4S on October 7, 2011 in seven initial countries (United States, Canada, Australia, United Kingdom, France, Germany, and Japan) with a first delivery date set for October 14, 2011, and available on that same day for direct store sales in those countries. It will be released in 22 more European, American and Asian countries, including Ireland, Mexico and Singapore by the end of October. Finger cross for latest invention by Steve.
Out of your list I would go for the iPhone. I currently have the HTC Desire HD. Lovely phone, I personally have tried iPhone and HTC and I believe HTC is way better functionality wise, however visually, the iphone is fancier!