The HTC One and Samsung Galaxy S4 enjoyed some alone time as the top flagships, but their position on top is now threatened with several new entrants including the Sony Xperia Z1. The Xperia Z1 comes with several advantages like its faster processor, improved camera and optimised user interface. While Sony has also done a great done with the design, we tend to favor the aluminum unibody design of the HTC One.
If money is not an issue, the Xperia Z1 is definitely one of the best all round flagships in the market right now. However the HTC One is now much cheaper than when it first entered the market and will make a good investment for someone looking for a flagship quality device at a reasonable price.
You can check out a detailed comparison between the Sony Xperia Z1 and the HTC One on PhoneArena.