OptiPlex 7010. I like it. You can search their current inventory here:
http://outlet.us.dell.com/ARBOnlineSales/Online/InventorySearch.aspx?c=us&cs=28&l=en&s=dfb&brandid=2802
You can usually find about what you want with processor, memory and video options. I went with the mini tower form factor because it is easier to fit new graphics cards in the full-size form factors.
There is an OptiPlex 7010 with an i5-3470, 8gb of RAM, Windows 8 Pro, 500gb drive and an AMD Radeon 7570 for $669. That includes a 3-year NBD warranty.