Another is from a relatively new company called OnePlus. They've received some bad press, but have a great smartphone called the OnePlus One. Even if the pre-order system was a mess, it's a decent phone. Their approach is offering an excellent device with nearly stock Android, or the popular CyanogenMod. A team that's been developing Android software and 3rd party ROMs for years, but has recently gone commercial.
The OnePlus One is essentially one of the best phones from this list, and is only $299. It has a 5.5-inch 1080p HD display, a powerful Snapdragon 801 quad-core processor with 3GB of RAM, a 13 megapixel Sony camera, 4G LTE, and a large 3,100 mAh battery. All of this runs Android 4.4 KitKat and is only $299. There's also a 64GB model available if you have the extra cash. This is probably the next best thing compared to the Nexus 6.