Which Gaming PC Build?

I am building a gaming PC (but it won't be used only for gaming). I have two builds that I am considering. The first has an i7-6700k with a 980 for 1080p and has a better mouse. The second build has an i5-6600k and a 980 Ti for 1440p. My worry with the second build is that the 980 Ti won't be enough for 1440p soon. And also if I ever need to add another in SLI I'm afraid of the i5 being a bottleneck. Both monitors have G-Sync. Which build would you recommend and why? Thanks! (Budget: ~$2000)

FIRST BUILD PCPartPicker part list: http://pcpartpicker.com/p/ydDBf7
Price breakdown by merchant: http://pcpartpicker.com/p/ydDBf7/by_merchant/

CPU: Intel Core i7-6700K 4.0GHz Quad-Core Processor ($334.99 @ Newegg)
CPU Cooler: Phanteks PH-TC12DX_BK 68.5 CFM CPU Cooler ($47.99 @ NCIX US)
Motherboard: Asus Z170-A ATX LGA1151 Motherboard ($134.99 @ Amazon)
Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-2666 Memory ($57.99 @ Amazon)
Storage: Samsung 850 EVO-Series 250GB 2.5" Solid State Drive ($87.77 @ OutletPC)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($46.98 @ OutletPC)
Video Card: Gigabyte GeForce GTX 980 4GB XTREME GAMING Video Card ($489.99 @ Micro Center)
Case: Phanteks ECLIPSE P400S ATX Mid Tower Case ($79.99 @ Amazon)
Power Supply: EVGA 750W 80+ Gold Certified Fully-Modular ATX Power Supply ($89.99 @ Newegg)
Wireless Network Adapter: TP-Link TL-WDN4800 802.11a/b/g/n PCI-Express x1 Wi-Fi Adapter ($37.98 @ Mac Mall)
Case Fan: Corsair Air Series AF120 Quiet Edition (2-Pack) 39.9 CFM 120mm Fans ($25.88 @ OutletPC)
Monitor: Acer XB240H ABPR 144Hz 24.0" Monitor ($415.55 @ B&H)
Mouse: Mionix Castor Wired Optical Mouse ($69.99 @ Amazon)
Other: Windows 10 ($27.99)
Other: Extended Mouse Pad ($15.99)
Other: Anti-Static Wrist Strap ($1.96)
Other: RGB Desk LEDs ($20.99)
Other: PC LEDs ($14.99)
Total: $2002.00
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-05-03 07:57 EDT-0400

SECOND BUILD PCPartPicker part list: http://pcpartpicker.com/p/RJhC23
Price breakdown by merchant: http://pcpartpicker.com/p/RJhC23/by_merchant/

CPU: Intel Core i5-6600K 3.5GHz Quad-Core Processor ($233.99 @ SuperBiiz)
CPU Cooler: Phanteks PH-TC12DX_BK 68.5 CFM CPU Cooler ($47.99 @ NCIX US)
Thermal Compound: Arctic Silver 5 High-Density Polysynthetic Silver 3.5g Thermal Paste ($5.88 @ OutletPC)
Motherboard: Asus Z170-A ATX LGA1151 Motherboard ($134.99 @ Amazon)
Memory: Corsair Vengeance LPX 16GB (2 x 8GB) DDR4-2666 Memory ($57.99 @ Amazon)
Storage: Samsung 850 EVO-Series 250GB 2.5" Solid State Drive ($87.77 @ OutletPC)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive ($46.98 @ OutletPC)
Video Card: Gigabyte GeForce GTX 980 Ti 6GB Video Card ($626.98 @ Newegg)
Case: Fractal Design Define S w/Window ATX Mid Tower Case ($72.99 @ NCIX US)
Power Supply: EVGA 750W 80+ Gold Certified Fully-Modular ATX Power Supply ($89.99 @ Newegg)
Wireless Network Adapter: TP-Link TL-WDN4800 802.11a/b/g/n PCI-Express x1 Wi-Fi Adapter ($37.98 @ Mac Mall)
Monitor: Dell S2716DG 144Hz 27.0" Monitor ($489.99 @ Amazon)
Mouse: Logitech G502 Wired Optical Mouse ($49.99 @ Best Buy)
Other: Windows 10 ($27.99)
Other: Extended Mouse Pad ($15.99)
Other: Anti-Static Wrist Strap ($1.96)
Other: RGB Desk LEDs ($20.99)
Other: PC LEDs ($14.99)
Total: $2065.43
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-05-03 07:59 EDT-0400