Most restaurants use peanut oil when they deep fry foods because of it's high smoke point and it does a good job at frying the foods and is a pretty healthy cooking oil to cook with.
Some other restaurants may use Canola Oil to deep fry foods but the majority of the restaurants and the restaurants I've worked in as a cook used peanut oil to deep fry the foods.
Peanut Oil has a smoke point of 450 F degrees which makes it a great oil to deep fry foods with.
The Canola Oil has a smoke point of 400 F degrees which makes both those oils a good oil to cook with and they will remain stable while cooking.