Do I file H1b petition for change of status or consular notification?

Guys,

I am currenty on F1 OPT extension which expires on June 2015. My employer is ready to file H1b petition for me but are asking to choose between H1b petition for COS or consular notification. Which option would be better for me? Are there any risk for visa stamping If I chose consular notification? Please advise. Thank you.

-Mohan