The phrase 'over that of' is correct and usable in written English.
You can use it when comparing or contrasting two things. For example, "I prefer the climate in California over that of New York."
You must be able to communicate your value proposition over that of your competitors.
Loaded With Debt Japan's debt-to-GDP ratio towers over that of other countries.
Her displacement and beam were increased over that of her half-sisters with slightly less draught.
June's gas cost of 52.1 cents per therm is about 26% over that of June 2000.
Root development is long and clearly advanced over that of the remaining permanent premolars.
The N50 of the final EST set improved over that of the redundant ESTs (Table 2).
Use your ad to highlight your product's advantages over that of your competitors.
Gen. George H. Thomas's corps over that of Maj.
Robbie Keane's hangs over that of Harry Kewell.
But why take a pupil's evidence over that of Raphael?
At the Helsinki summit, Trump even took Putin's word over that of the U.S. intelligence community.
