I'm all for velcro
. For the vest, I use 'sew-on' velcro that I attach with liquid stitch fabric glue, then I just sew down the corners so they don't peel off. Then I go with industrial strength adhesive velcro for the plates, which, for the most part, are usually metal. Even when I was going with unnecessarily heavy 16ga steel chest plates, the velcro held up pretty much forever.
To get the industrial velcro to fasten properly, you have to sort of wiggle it a little, moving the plate against the vest, but once you do that, it holds quite secure. It's kind of a chakaar to pull the plates off afterward, but I've never had a problem with the plates coming off randomly, not even when a corner of the armor plate has caught on something.