Samsung continues to dazzle the world with its top-selling Galaxy S4, which in some parts of the world is endowed with Samsung's Exynos octa-core SoC running at 1.6GHz. Here in North America, it's built around a paltry quad-core Qualcomm Snapdragon 600 at 1.9GHz with 2 GB of DDR3 RAM. Samsung's flagship smartphone also delivers an impressive mixed-use battery life that goes on for days. Its 5-inch display puts out full HD -- an amazing 441 ppi at 1,920 x 1,080 pixels. Also impressive is its 13MP rear camera with 4x digital zoom, which takes beautiful, vibrant photos. Both of its cameras can capture 1080p video at 30 frames-per-second, and both can record video or take pictures at the same time. And Samsung's smartphones are still the only ones that can display more than one app on the screen at a time. The Galaxy S4 is available for AT&T, Sprint, T-Mobile and Verizon for around $49 with a contract.