While Mobile Legends is certainly popular than other mobile MOBAs, but i would have to respectfully disagree you on it to be the best moba app xD.
With Vainglory coming 5v5 early access 2 days after and global release in mid february, It is going to be the MOBA to look out for(opinions).

Vainglory's graphics and controls are far above Mobile Legends with its cartoony graphics and joystick controls.
And the best of all, Vainglory is completely free. Not even a dime necessary.
Of course, those skins are optional. They do not affect your progress.

Give Vainglory a chance :)

Again, my Opinions only.