I have one PC build under my belt, and I'm slowly upgrading as my wants and needs for the computer grow. First round, I bought a EVGA 560ti, works great. I really only play one game, EVE Online, and I play 2 clients at max graphics and it does just fine. It doesn't handle 3 clients max graphics well, and also doesn't support three monitors.
Here are the points of reference
1. EVE Online
2. 3 monitors
3. 200$ max budget, 210 if its a steal. (USD)
The HD7950 and 7870 use different chips (Tahiti and Pitcairn respectively) hence the variations.
The HD 7950 is the fastest overall but stock is limited so you may find it difficult to source one at a reasonable price. Also avoid any using a single fan cooler design except the HIS IceQ one.
the HD7870 isn't as fast as a 7950 at stock speeds but can get close to a stock (800/1250 MHz) 7950 if it's overclocked or one of the GHz Edition cards. Naturally the 7950 pulls ahead again when IT is overclocked.
Of the three you linked, the GTX660 is probably the weakest overall but AFAIK Eve does prefer Nvidia hardware, so if that is your game of choice I'd go for the GTX660. Also EVGA has a legendary customer support team and attitude, which you may find more attractive than a lower price or better overall performance.
Obviously, check the card you have in mind will connect to your monitors...Obvious but easily overlooked.
+1 to coozie 7, I have heard this that EVGA has top notch customer service.
But if u want to game at dual monitors or want the best performance at 1080p, then HD7950 is the card you are looking for.
But if you only want to game on single monitor and get the best out of ur money then also the cheaper hd7950 with better cooling, greater bus-width would be perfect.