I bought a pot of Magnesium Ascorbate; the arguments being:
1. It's one of the better assimilated forms of Mg, although not the best.
2. It also delivers Vitamin C, so two vitamins for the price of one
.
3. It was really cheap.
However - as I mentioned elsewhere, you have to be careful if making it into a drink rich with citric acid (eg, Lemonade made with fresh lemons) as it converts to Magnesium Citrate in your guts, which most definitely has a purging effect on the intestines
.
One of the "side effects" I get of a LCHF diet (which changes electrolyte balance/requirements profoundly) is twitchy muscles, and cramp - and this stuff goes a long way to fixing it; also helps with restless leg syndrome.