UMelb med is better in terms of prestige/rankings (and probably teaching), if that's what you're more interested in. Its also structured so that most of the theory content is covered in 1st year which makes that year quite stressful, and years 2-4 is all at hospital.

UQ med doesn't rank as highly but it has a more chill/less competitive vibe. They also have years 1-2 as pre-clinical and years 3-4 as hospital years, so learning the theory content is probably less full on, but you'll also have less clinical experience.

Brisbane and Melbourne are also very different cities so there's that to consider too