I think he's a bit weaker based on Base Trunks being able to blast him out of the city.
Base Trunks (Cell) < Base Kids (Boo), and the kids are on par with 18. Cell states he is above 18, and Trunks can still send him flying in Base. I think Future Cell kind of has to be close to 18 based on that, but still superior.
I don't have a problem with future Cell being equal to Ginger Town Cell. The only difference was that GT Cell lacked an aura while the former not, but I don't think this shows us for certain that future Cell > GInger Cell. It's possible that AT did not even remember of Ginger Town Cell lacking an aura.