It depends on where I'm managing. If it's somewhere in Eastern Europe, it's Mikhail Belukhin. In England it's Daniel Brockley. In the Netherlands it's Jan de Groot and so on.
I have lots of names myself:
Aleksey Tarasov - Russia
Puiu Gãina - Romania
Henri Leveque - France
Juan Delgado - Spain
Imre von Winkel - Germany
Nero Garnerus - Latin
Alois Lautens - Swiss
Kimitomo Ichijo - Japan
Gianni Rizzo - Italy
Antonio Ramirez - Mexico
Qianfan Liu - China
Xenos Tsamis - Greece
Pepe Santiago - Spain
Mladen Jelic - Serbia
I use my own name always, i could invent some random names but my own feels to me most natural. Also, after I finish college, I'd like to learn to become a football coach, so I don't need random names...
If I'm starting a career with my Fav Club (Sheff Wed) then I will always use my real name. Rest of the time, I make one up. Im currently managing Accrington Stanley. My name in this save? Sebastian Guerrya. No idea if it even a proper surname!