>750ti
why would you not
because a 750 ti is a horrible option at $200? and at $150, too. only good if you find one on sale at around $100, otherwise, there are way better cards around
OP, if you don't mind doing rebates, theres a $70 Powercolor R7 260X on newegg, it will smoke through source games at a VERY high FPS (hell, i can pretty much max out TF2 at 60FPS with Intel HD 4600, source engine runs great on anything)