All would be the same if they had baked long enough to come to an equilibrium temperature all the way through in the oven. Heat won't pass from a cooler to a hotter. Ask Flanders and Swan. Second law of thermodynamics.
That said, it does assume that the food doesn't give off its own chemical energy when heated enough. Notice what I say about candied items.
If what you mean is which one will go on burning your mouth longest after dishing up, that has to do with how much heat it can store and how fast it can lose it etc. It also could be an effect of how much heat it is generating. For instance, a nicely caramelising piece of candied sweet potato (yams and similar roots) gives off a lot of chemical energy as well. It could take the skin off your palate after a potato of the same size could go down like a mouthful of salad. (SMALL bites, if you know what is good for you. You get more of the taste that way too!)
Apart from chemistry, how fast a bit of veg cools down depends on many factors, including its shape (frondy things cool fast, e.g. broccoli) and so do slender ones (e.g. green beans). Dense, large items with lots of water, especially with their peels intact so that they cannot cool very fast by evaporation (potatoes, yams, whole onions) certainly are the worst as a rule.
Ouch!
Jon
