Spot weld cutter

[DRJDVM's '69]

I'm looking for a spot weld cutter/bit.

I've looked at several at Eastwood and was wondering if anyone had some suggestions. It looks like there at basically 2 types.... one is basically a large drill bit and the other has a drill bit in the center and a larger cutting ring on the outside of that.

So any tips on which works the best with the least amount of damage to the remaining sheetmetal. I'm getting ready to get rid of the rusty trunk pan in the Barracuda.