Why did I forget to mention this?

This is the way I did it for years, but I guess maybe the plumbers pliers feels faster in recent times.

I often work late into the night, which also skews my preference away from using a hammer.

One thing about lockrings and headset locknuts is that they flex in response to tightening forces from tools.

So, if the lockring/locknut material (aluminum?), or the tool interface limits the application of torque, one can get these things to stay put by repositioning the jaws to different positions around the nut/ring, with each successive tightening allowing the flexible nut/ring to creep a bit further towards tightness. I find this useful for preserving the new condition of nice alloy headset top nuts.
It works the same way with my old-fashioned drill chuck, where I can get the best grip on the drill bit by securing the chuck from each of the three pinion holes, thus pushing the gear ring from different directions so as to settle more fully toward tightness on the bit.

But I agree that the lockring pliers look like they would do the best job with the least effort.