And he insists the Ibrox club are the biggest out of the two.
The striker won a move to Elland Road due to his goalscoring exploits at Oxford United and would eventually end up in Glasgow via Anderlecht.
Both of his former sides are now owned by 49ers Enterprises but Rangers win the battle when it come to size, says Roofe.
He explained his thinking too - because his former club have fans all over Scotland, England, Ireland, Northern Ireland and even further afield.
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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 he was asked who he preferred playing for out of the two, and laughed: “You’re really trying to kill me here.”