If we get all the applications, then it seems that Freezing can take things to absolute 0 (0 degrees kelvin, where the molecules have no kinetic energy whatsoever), and Heat Generation can take things to 'absolute hot', where things are so hot our models of physics break down. Now, we're already capable of taking things very close to absolute 0, though it is fundamentally impossible to go to 0 due to quantum mechanical effects. On the other hand, we really can't take anything to anywhere near 'absolute hot'. So from a scientific perspective, I think Heat Generation could teach us more.

There's also the fact that Heat Generation basically creates energy for free (assuming it's not coming from elsewhere), and thus can essentially reverse entropy, which is nice.