But it's DBZ... So it works lol.
Anyway, depends on which first form Cell we're talking about. The initial fight he had with Piccolo MAY be weaker than final form Frieza, but after absorbing the citizens of Gingertown and a few other cities, Cell stomps. He was stronger than Piccolo who was stated by Vegeta himself to be even stronger than Vegeta.
SSJ Vegeta got wrecked by 18, who is inferior in strength to number 17. 17 was roughly equal with Piccolo before his Stamina decreased, but Cell after absorbing all those humans pretty easily blew a hole in Piccolos chest. So....
Math again? Frieza< Goku at this time period< Trunks<Vegeta<18<17=/=<Piccolo<16<Cell.
Cell wrecks.