We almost need more info. If you already own the GPU then there is the reason. Otherwise I'd vote for a GTX 1060 or Radeon RX480. I'd get the RX480 just for the simple fact that Freesync monitors are cheaper.
One of the newer video cards will also allow you to get away with a lower wattage PSU. The EVGA G2 or G3 series are a good value for high quality. The G3 series are new so there may be deals going on to clear out the G2's. 500W would be enough with a 1060 or RX480 video card, even enough for a 750Ti but I'd probably look at a 550-650W for the 750Ti just to play it safe.
As for a case any mid tower ATX will work. It depends on your budget and what case you like the looks of. The Fractal Define R5 is nice, and the Define S is the same case without drive cages so you save tons of money but have the same quality. The define S is for people who don't need a cd-rom or use an external one, and who want the extra room for water cooling and want to save money.