Magnesium malate is a very good form, the malate part is malic acid, which is important for the krebs cycle (energy production), and might be able to detoxify aluminium.
Plus, yeasts (pretty sure candida is in the list) often produce tartaric acid, which competes against malic acid.
Magnesium malate has been known to be very useful with fybriomyalgia, which might be linked to candida, at least as a contributing factor.