Hmm, I dunno. I guess I had roughly the same choice when I wanted my first buckling spring, but it was biased by the fact that I could get the IBM here vs paying hefty shipping and taxes to get a Unicomp sent over from the US. Have a read up about
bolt-modding the IBM before you decide, because that fixes the most likely fault you'll find with a Model M, which is broken plastic heat-stakes (aka rivets).