I usually just grip the shaft with a good pair of vice grips.
I think the nut is maybe a 21 mm....aftermarket nuts are different size. ...but vary from manufacturer to manufacturer.
To be honest..that past few sets I've done I just get the loaded versions
I may try the vice-grip option for removal if I can't round up an impact gun. Curious, how did you tighten the nut on the new strut?
I strongly considered quick-struts. Some report satisfactory results, others not so much. I was concerned about installing new springs in the front as where the rear OE leaf springs would remain. For example, one guy said his new quick-struts raised his ride height by two inches. Although, I'm sure new springs would probably settle over time, I didn't feel like rolling the dice on that one. Currently, my ride quality is not too bad and no sagging that I can detect so I'm hoping my OE front springs will get a few more miles out of them.