for earning 20 pips per day, which is the best time frame ?

 
It is not a matter of time frame but it matters what strategy you will you use. Time frame is related to the strategy itself. So, it comes the second in importance. So, no vote for me!.
 
no vote for me either for 20 pip a day you don't need a time frame.
 
Depends on strategy
 
Depends on the day. LOL
 
It depends on your experience and emotions
 
For only 20 pips wait for momentum with the trend   ( Daily )
 

It is better to think about higher time frame at least 1 Hour!

based on price action and many strategies the 1 Hour can be good for that goal!

 
Mohammad Rahimi:

It is better to think about higher time frame at least 1 Hour!

based on price action and many strategies the 1 Hour can be good for that goal!

+1
Reason: