Frieza's Death Beams can be fired several, if not dozens, of times in rapid succession. So Frieza should be capable of beam-spamming Superman to death with a barrage. Even if Superman can regenerate every laser, he should still be weakened enough for Frieza to finish him with a Death Cannon (his energy wave technique).
If Frieza can transform, he can go up to 3rd Form which is much stronger than his 2nd form...which is already 2x First Form, and he will also regenerate any battle damage to a certain degree by transforming.
Debating Heat Vision and Frost Breath effectiveness kind of depends on how hot/cold they are. Frieza could endure Namek's explosion when nearly dead and survive the cold reaches of space. So I assume his Heat Vision needs to be hotter than lava, and his Frost Breath should be colder than space. If they aren't, they are just glorified attacks which Frieza can tank.
It's also worth noting that Frieza can survive just about anything, short of vaporisation. Superman is going to need to blow Frieza to pieces, at least, to kill him.
I'm not really seeing any notable abilities that Superman has, just a ton of really nice resistances that aren't relevant to Frieza's own abilities.
Overall, I'm voting Frieza, unless something works in Superman's favor.