I have a couple nice angle grinders and good thin cutoff wheels...
I reach for the portaband just about every time. Only occasionally does the angle grinder have better access and is then tool for the job. Or for something hardened.
In comparison the portaband is quiet, calm, controlled, and easy to cut to a line. The angle grinder is loud, throws sparks and sometimes chunks of disc, and takes more skill and control to cut carefully with.
Also portaband blades last and last, months if not years depending on use, and cost about $10-20 each. Cutoff disc last more along the lines of how many cuts/jobs and cost about $1-2.
Both are good tools and have varied uses that overlap only slightly. If you have not tried a portaband I expect once you do you'll add one to your wish list.
