The striker, who has played for both clubs, says the Ibrox side have a larger fan base.
He moved to Leeds United from Oxford United after impressing with his goal-scoring abilities before joining Rangers via Anderlecht.
Both teams are now owned by 49ers Enterprises.
However, Roofe believes Rangers are the bigger club due to their worldwide following.
Read more:
He said: "Both of them massive, massive, massive.
"Anywhere I go in the world I will bump into Rangers or Leeds fans but fanbase-wise I would have to say Rangers because Leeds is just Leeds.
"But Rangers is people in Glasgow who support Rangers or Celtic and then outside of Glasgow, Scottish people will support their local team plus either Rangers or Celtic.
"Then you go to Ireland, Northern Ireland.
"It’s one of the two again.
"And then you come to England and they have an English and a Scottish team as well so there’s more people who seem to support Rangers whereas Leeds fans are pretty much from Leeds.
"It’s down to Rangers having the ability and more scope because they have English people who have a Scottish team as well."
Roofe was then asked who he preferred playing for out of the two, and laughed: "You’re really trying to kill me here."