Spot weld cutter

I've used grinders, sanders, die grinders with carbide burs, and spotweld cutters. I've tried regular drill bits, but just got frustrated since some times then weld just isn't uniform enough and there too much material still attached for the drill bit.

For me, it depends on if I plan on re-using the panel. If so, I prefer the Blair spot-weld cutter just because it leaves such a clean hole. If not, grinders, sanders, and carbide burs all work well. Pick your poison.