NR before sharpening always.
You do realize that the order of application makes no difference to the final result, correct? It may make a difference to what numbers you end up choosing and how you choose them, but the application order is hard coded into the Camera Raw code.
Hm, I have always liked the results better that way, and I have watched a few tutorials back in the day, and at Adobe they have said, always start with NR so you don't sharpen the noise, but remove it first. And that makes sense so I have always done that.
In Lightroom (or Camera Raw), it doesn't matter. The final numbers are all that matter.
Try this. Apply 100L-NR and then 100 sharpening and export an image. Then reset and apply 100 sharpening and then 100L-NR and export again. Now, compare the final images. They will be identical.
Note that doing the same in Photoshop (not using the Camera Raw plugin) WILL depend on the order of application.