which site is the best for mining?
I see that you are quite new here so let me try and help you. Mining is done by using highly sophisticated machines called the Asian, so it is pretty sure that for you and for me would be completely unprofitable.
When you are talking about the site for mining, I guess you mean the site for cloud mining. There are many services out there. Let me warn you that if you for get into cloud mining, majority of the services out there are complete scams. Do your research well and don't get screwed.
As you can see, mining in Bitcoin for the average people is over with. I suggest that you read and learn and get involved with Bitcoin in some other way besides mining.
Good luck!