Anime-wise, I'd probably give it to Freeza. Goku noted that he and Vegeta wouldn't get much out of the Rosat training from having reached their limits, so Goku would be at best marginally stronger than the version of him who was still noticeably behind Golden Freeza. Manga-wise, Goku probably wins due to such not being noted as well as it being vague how much stronger Freeza was than them, if at all.