Look at the Brother brand.
I've started to hear grumblings about modern Brothers, like finally locking out third party toner trays... but yes. QFT. Brother's the least crappy maker on the market still.
What you'll want to look for is a B&W toner MFC model with duplex capability:
MFC-L2900DW, MFC-L2820DWXL, MFC-L2750DW
...unless you just absolutely need color. Then get an extra fancypants CMYK color toner model:
MFC-L3720CDW, MFC-L3780CDW, MFC-L8610CDW
...and be sure to turn on toner saver in the print drivers for default printing.
(Sorry, the URLs from Brother's website seem to break BBCode URL linking due to all the brackets. So, I just named the three cheapest models of each type that are shown as new in stock with prices.)