In general, using an impact will be easier than hand tools because the quick burst of torque so that the chance for the ball joint to spin in the housing is much less. I have had a couple stubborn oned that cutting it is the only option.
Most after market stabilizer link now has a tab that sticks out so that once the tab turns and hit against the side of the mounting tab/hole on the strut, it will stops the joint from spinning as you loosen the nut. The stock ones may have an Allen key/wrench hole on the center of the bolt, but lots of time, the nut seized so bad that nothing going to loosen the nut.