Well, there are two main reasons.

The first is that Toriyama simply just likes Frieza more than Cell. Frieza is the most iconic villain in Dragon Ball and is one of the most iconic ones in anime. Frieza has a history with the Saiyans, with the genocide and everything, and recently, destroying Mastered Ultra Instinct Goku and Ultra Ego Vegeta, and also, Toriyama hates drawing the black dots for Cell.

The second is Frieza’s Golden Form. Frieza has an insurmountable growth rate, and a recent example came up, showing Frieza training in the Hyperbolic Chamber of Space and Time, while squeezing in TEN WHOLE YEARS into himself.

This was also a product of his training, and his training only.

Meanwhile with Cell, he was getting his ass kicked by teenager Gohan. That’s not good enough to compete with Frieza, who is dealing with beings like Jiren and Goku, who got stronger from the Cell Saga. Cell also required stolen power from other androids and beings to increase his own power level. When he was in Cell Max, he still got kicked around by Gohan. Cell’s era of power had passed, as Goku had shown that he could easily contend with Cell.