I kind of like the English pronounciation of it, MIR-ee-am, with a short first syllable. I had a friend called Miriam, but as we're German, we pronounce it, of course, MEE-ree-ahm, and I dislike the name in German. In English, I think it's very cool, and not common, so it's nice to see on a girl nowadays. My friend frequently got called Miri (MEE-ree), and I definitely prefer Miri to Mimi which I just find ridiculous, to be honest. But, if I could decide, I would either choose a completely different nn or none at all. And who says you have to pick a nn for your child before it's even born? In our family, they've always kind of developed... Some people stick with nns that aren't even close to their fns, but somebody started to call them that and it stuck... I think I'd find Mim (MIMM) very cute as a nn for Miriam, btw. Or Miri/Mirry/Mirrie pronounced MIRR-ee, short first syllable. Or Ria/Ree.