Scenario 1: You and your best friend are kidnapped. The kidnapper gives you the choice of:
A) Your friend performing oral sex on you and him.
B) You performing oral sex on your friend
I rather give than receive
Scenario 2:
A) Having to do ass-to-mouth everyday for week with your ass
Rather have it be my own ass, at least I know how I take care of myself 
B) Do Ass-to-Mouth with another sub's ass
Scenario 3:
A) Perform one of you limits
I rather perform one of my limits than have my face in a video or picture, possibly going around the internet
B) Perform one of your dislikes on video with your face
Scenario 4:
A) Walk naked on a leash through a town of strangers in the middle of the day
B) Walk naked on a leash through your hometown in the middle of the night.
No one ever goes out at night in there
Scenario 5
A) Have someone piss and cum on your face and mouth
Very hot, would choose above many things 
B) Lick their ass
Bonus: What do you think is the more submissive act
A) Oral Sex
Performing oral sex is a matter of willingly submitting to someone and doing an action. Anal is more a matter of receiving.
B) Anal Penetration