Each of them have their advantages or disadvanteg, I am focussin gon a healer monk, but if I find some nice suggestion about prot monks I might go that way. Please note this is mainly for HoH.
Ele/Mo would mean you have more energy but you heal for less of an amount which makes me think having monk as primary is more effecient healing and energy wise.
Mo/Mes would mean you can place 1 skill which will give you an energy boost whereas Mo/ele would mean you can place 1 word skill. Having a word skill would mean you need to place attribute points into earth magic which could be a disadvantage.
I am still not sure of which is best to go for; as we all know there is no "best" monk build but any suggestion on why you prefer one more than the other is welcome.