Central defender O'Brien, who has started in all five of Leeds' matches since arriving on loan from Bolton last month, also feels several other players at Elland Road would not be out of place in the Barclays Premier League.
O'Brien, 31, said: "I think Jonny Howson should have had a place in the last England squad because he's playing as well as any midfielder in England.
"He scored a great hat-trick at Scunthorpe and he's a really talented player. I can't believe Robert Snodgrass isn't a regular in the Scotland squad either.
"If I'm honest it has surprised me, I was expecting a good standard, but I have been surprised how tough the Championship is.
"I think many of the players in the squad would be fine going straight into the Premier League and some of them even further than that."