DIFFERENT ARDUINOS

I want to chosse between Arduino uno and mega and due ?
which one i should use for my project?
please tell me ..thank you in advance..

An Arduino Uno.

I agree. The Mega and the Due are more specialized. No microcontroller board is more compatible and supported than the Uno. So learn on the Uno. Get a specialty board when you know exactly which features you need it for.

(aw, you're messing with my "perhaps vague questions deserve vague answers" experiment!)

I like that style, and often hold back when I see it used. However in this case (and many others) I feel the vagueness and brevity may come from poor English skills. In such cases I like to provide more information to encourage exploration on the part of the OP.