Lenovo C50-30 (F0B100KUUS) All-in-One Desktop
If you find this computer for $850, then it's a pretty good all-in-one computer, but if you find it for a lot lower price than that, then it's probably the best value on the market. You get a 5th Generation Intel i3 dual-core processor and 8GB of memory which gives you very nice performance overall. You're probably not going to be running the latest PC games on this one since it lacks any dedicated video memory. However, it should work well for a wide range of general programs and some games with lower requirements.
The 23 inch display that comes with this computer looks great and though you can pay more for a model with a touchscreen, this is a standard LED display. You also get a DVD burner, 1TB of storage, and this system has both Bluetooth and Wireless-AC compatibility. If you find this model from Lenovo or a retailer at just $550 then it's an incredible value that you should not overlook.