what is the best way to take from baiyun airpot to shenzhen?

It depends on your destination in Shenzhen.
There are direct intercity buses between the airport and Shenzhen Bagualing. If your destination is nearby, it should be the best choice. If not, it is suggested to take airport shuttle bus line 6 to East Railway Station, where there are direct bullet train to Shenzhen Luohu.