I am using the service from
http://www.gurufi.com/ and I choose the editor Brian.
I get to know this service from this thread, see below.
http://forums.studentdoctor.net/threads/best-websites-for-editing-personal-statements.803384/
Brian is highly helpful. I am working as a research scholar and work at least 50 hours per week in a lab. I cannot focus on writing the assays even for a whole morning or afternoon. When it goes to night, I am too exhausted after the lab work. Under my condition, you definitely need the online editing service.