I would like to buy pingpong ball but i am confuse to select it which one a good one and heavy one Could you please describe for me And also i would like to change the rubber what brand is the best

Nittaku 3 star balls are for professionals. 3 of them costs $10.

TO ME the best ball is Gambler. Inexpensive and good enough for the average player. Other people will prefer butterfly or nittaku (always 3 stars quality). Assuming you are new to the game I suggest go for an alaround inexpensive rubber. It would be bad for you to get an expensive rubber designed for experts. Once you learn the game you won't need advice. You will know.