ENBSeries

I have iPresentInterval set to 1 (enabled because I experience no major input lag) which should in theory cap the framerate to 60. But the problem is that it doesn't, maybe because I'm running the monitor in generic non PnP (monitor is too old, drivers don't work) and the game doesn't detect the refresh rate or something.

Which leads us to the question, what is the best way to limit FPS? Is it best to use NVIDIA's adaptive vsync, ENB vsync or just use the FPS limiter, either from NVIDIA inspector or ENB?

vsync must be enabled in enblocal.ini and in game video options. Monitors always support vsync, that which do not will not even work.
On my opinion, vsync is the best option for limiting performance, but not adaptive one.

Okay, thanks Boris. I actually still experience tearing with both iPresentInterval=1 and adaptive vsync, so I'll try what you said.

I still don't understand why Skyrim's vsync doesn't cap my FPS as it should, though.

Adaptive vsync do not fix screen tearing, that's why it called adaptive. And if fps is not limited to display refresh rate (60, 72, 75, 85 or what do you have), then vsync simply not work.

Gotcha. By the way now I use game's vsync and ENB vsync, tearing completely gone and no input lag at all.