The FX-9590 Is not very good for overclocking. It's best used at Stock settings, but it shouldn't bottleneck a 980 SLI Config. however, a water cooler is MANDATORY for the 9590, as it will heat up like hot coals on a grill. If you plan to go with a AMD AM3+ Processor, You are better off with the FX-8350. It's $170, runs at 4 Ghz, can be Overclocked to 4.8 with the right cooler, and shouldn't bottleneck the 980 SLI's at all.
As for the Core i7 4790K, It is quite a beast. You can over clock it to 4.8 Ghz and it will shatter the 9590 and 8350 in almost every category, not to mention that Intel CPU's are brilliant with SLI configs, so your SLI 980's will run like a dream. The only downside is it does cost more than the 9590 and 8350. (FX-9590 is $230 CPU only, But you WILL need a liquid cooler to keep it cool, so it adds up to maybe $300. The FX-8350 costs $170, where as the I7 4790K will run you $350 straight up.)
To answer your question, the FX-9590 is only for those who are hardcore AMD Fans. I would not recommend it because it just isn't the best option for Overclocking. The Intel Core i7 4790K Will do much better at stock and Overclocking, will run BF4 no problem, and is generally, for me at least, the best option with 980 SLI Configurations.
Simply put, Avoid the 9590, and get the Core i7 4790K. Yes, the i7 is expensive, but for the price, it is definitely worth it.