My view is that it doesn't matter and that the differences between companies are largely brand positioning. So some companies go for large volume - low margin - they sell cheap and market themselves as 'no frills'. Other companies go for low volume - high margin. They market themselves as 'quality'. But all essentially sell the same product doing the same thing, and the differences may not be worth fretting about.
I don't have any evidence for this, but I've watched manufacturers trying to spin creatine a thousand different ways in order to compete within a saturated marketplace.
I love creatine, but I can't tell a bit of difference in its effects from one brand to another.
Powerlifts: 500/363/573 @ 220 belt only
front squat: 403
dips: bodyweight + 176 x 4
military press: 232