I would think that also alertness, willpower, mind, focus, (con-)centration, mindforce can replace mana/MP, if you design the world so that one of them fits in. Furthermore, spirit, astral power, communion (for nature-based magic) could work.
On the other hand, player have been teached for decades that mana is magic power, so if you use something else, you must beaware that players will have a steeper learning curve (not much for one, but if you introduce too many new terms, it will sum up).