The T-Mobile HD2 (aka, HTC Leo) deserves a special pedestal in the pantheon of epic smartphones. Before Android became a real force to be reckoned with, Microsoft still felt that its Windows Mobile platform had a chance. Running Windows Mobile 6.5 when it debuted in 2009, the HTC HD2 came with weak software, but its hardware was anything but. Powered by a 1GHz Snapdragon CPU, 1GB of RAM (U.S. T-Mobile version), plus a large 4.3-inch WVGA screen, tweakers quickly cooked up custom Android ROMS for the device. I personally wiped Windows off of my HD2 in favor of Android 2.3 Gingerbread. Ah, those were the days.