"me-makan" make it sounds more formal, but to be honest, i almost never use it, sound very strange to me :)
Thank you for your reply! :) But is there a grammatical explanation on when to use which?
for this "me-" group i guess this is only used to make it more formal as it doesn't change the meaning
No real explanation except when you want to be more formal or give more emphasis. A bit like JOHN eats rice Vs. John EATS rice, the latter would require memakan. Even then, I have never heard any of my Indo relatives say memakan ... they only ever say makan.