Can I substitute sunflower/safflower oil for the canola oil in this recipe? Would sunflower oil make the cake taste better or worse?

I am with ChefOno on the smell of heated canola. It turned me off from using canola for any purpose. I generally use sunflower instead.

I'm also thinking that a decent quality olive oil would make a lovely cake, although then it would be a distinctly olive oil cake. But an olive oil cake goes wonderfully with roasted strawberries drizzled with a tiny bit of balsamic vinegar ;)

I use sunflower oil in baking all the time. I think it yields better results than Canola oil, and I've never been able to taste any difference. I wouldn't use a super expensive sunflower or safflower oil, that seems like a waste to me. I tend to save the premium oils for salad dressings and use the more refined for baking.

Sunflower and safflower are both good substitutes for canola for the purpose, assuming they are the typical refined versions commonly available at most grocery stores. You shouldn't be able to taste the difference over the other flavors in the cake with any such oil except maybe corn.

In my opinion, any oil would make a good substitution for canola for most purposes. That stuff is nasty (smells like fish) when heated and it's one of the lowest saturated oils available. Low saturation = affinity for oxygen = short shelf life + rancidity = free radicals = cancer.

I just made this cake yesterday! I used vegetable oil. I am not sure about safflower oil, I think any flavor in the oil will carry through to the cake because it is quite delicate, so you want to stay very neutral. By the way, it is excellent with the icing from sdebrangos Texas Sheet Cake ...