I need to remove some inner wheel well/shock towers that are spot welded in place. What's the best (quality) spot weld drill bit brand available or other method or tool? Also I may need to have long or extended length versions (6"+) as I may not be able to get between some bodywork to get to some spot welds with the drill head and wondering if there is something to do this? Thanks in advance for any help.

I have used a couple different brands over the years but to me the harbor freight one is best. Other ways are grind down thin/through at the spot weld. I use a whiz wheel or dynafile for ths, and sometimes a putty knife to pop them when accessible.

An air chisel with a flat paddle blade is the quickest way I have found. Of course, it destroys one panel and has to have plenty of room for access. But it can be a time and patience saver where and when it can be used.

Other than that, I use a good drill bit as often as not. I have the blunt bit spot weld bits and the toothed bits, too. Each has their place, and each has their issues. The biggest issue is to start the bit precisely in the center of the spot. There usually is enough deformation in the center to throw the start off. That leaves strong attachment around an edge that has to chiselled or ground into submission. No one I have ever tried is the best in all possible circumstances. And all of the high quality ones are really expensive. The drill bits may be your best and only choice to reach a long way.

I allways use the cutter type (tiny hole saw) with the spring point. I replace the point with a shortened 6d nail then drill dead center (3/32nds drill bit) of the spot so the nail stays centered. If you need tool longer use a socket and extension, 1/4” stuff works good, a little silicone holds it together. If you need the cut hole solid again use a roofing nail to weld it up, grind flat and just like new again

Just did this on a Bronco windshield hinge. I have a set of spotweld cutters This One but after about three of them, just got a 3/8 drill bit and cut the rest out (about 25) in less time than it took for the first three. It really depends on how nice a job you are trying to do and what you are trying to save, the top layer or the bottom layer.

Blair Rotabroach is what I have always used...