DSR is a huge resource hog. I understand that you have a 980, but if you want to conserve for other reasons (fan noise, etc) then you might not want to go with that.
Even though my rig can handle it just fine, I do not use MSAA at all or the new NVIDIA MFAA (turn this on using the NVIDIA control panel or GeForce Experience) because I don't like the way it looks. I use post-process AA on ultra, along with everything else on ultra + a few tweaks in the NVIDIA control panel.
Check out this page for more in-depth info relating to DAI specifically, and this page for tweaking NVIDIA settings in the control panel. Keep in mind that you should adjust things so that you have the best performance for your rig, your monitor/tv, and your own eyes.
That said... probably the best, prettiest, and most natural looking AA will come from using DSR since the scene is rendered higher and then lowered to fit your own resolution. So if your rig can handle it, I might suggest trying NO MSAA (and no MFAA) + 2x or 4x DSR and see how it looks. Experimentation is the key
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