Upvote:1
Look at what happens to your mind through chanting them.
I find 'Om mani padme hum' powerful because of the deep yet concise rememberance, discussed here: What is the meaning of 'Om mani padme hung'?
But I found a Hindu mantra in English that I really connect with 'I am not this body, I am not this mind: I am, I am, I am'.
It is more important to really chant, with commitment, to follow the experience, than to pick and choose words though.
Here is a teaching letter from Seung Sahn on mantra practice.