IMHO, The 7970 should be your primary choice, thanks to the driver update that boosts its performance compared to Kepler GPUs. Not to mention, the higher overclockability! It'll be perfect for a multiple-monitor setup.
Kepler GPUs are pretty bad Overclockers compared to ATI's Tahiti 7000-series! The only reason you should go for the Kepler series is because of its Power saving features. And, Ironically.. these very features reduce the OC'ability of the Kepler-series.
I myself have a 660ti, But the only reason i picked it over a 7950 is because i was getting a free copy of Borderlands 2 at the time. But now and then, i feel like i should have picked the 7950 (or the 7870 even!)
I'd suggest going with the 7970 because at this price.. its got One Major Blessing: Horribly Amazing Value!!