Which vessels carry oxygen rich blood?
Short answer: The arteries
All blood vessels carry equal amounts of oxygen, the only difference is the size of the vessels.
There are vessels called arteries, they are the biggest ones, and that's why it is dangerous and often lethal if one is breached.
So since arteries are the biggest vessels, you could say that they contain more oxygen.
However, percetage-wise, they carry an equal amount as all other vessels.