Veritas Mk II as my favorite by far. I dumped the many many jigs and machines I had before. I mostly use it when changing the angle or a really messed up blade. ( carpentry chisel) It is handy on really thin or narrow chisels and irons that are hard to feel the bevel by hand I made a wedge to help set up skew chisels. Just don't go crazy tightening it down as you can bend the crossbar. I do have a DIY jig for my scrub plane. What I have learned in the last year is the angle is not really as important as we tend to think. For example, a bevel down plane, it just has to clear.
Few things need to be really square. Most just strait. Rabbit planes maybe. #45 irons.
I had an M-power jig and it did hold square. I do most of my work by hand now. With a little practice, it is easier and quicker.
FWIW, as I do more and more hand work, I have come to trust and appreciate the better tools. Veritas, LN, Narlex, Froip, etc. I used to think a well tuned mid range was good enough, and they are, but moving to the really well made does make a difference. Ironic, as I use sandpaper less and less, it is an area that has made tremendous strides.