Year 12s: what will be the first way you research your future options? >>

Southampton vs Anglia Ruskin

Which one is better for Medicine in terms of course content, student satisfaction, graduate prospects etc...

When it comes to medicine, the only real thing that will make a difference is course structure, teaching style, and location. All of those are personal preference.
Graduate prospects are identical, as when you apply to a FY1/2 post, applications are blinded to where you studied, so they will not know where you're applying from.

Look at the university websites, look at ranking for student satisfaction, go to open days etc.

Also, if you've not applied yet, and are looking at 2023 entry look at entry requirements. Medicine is obviously competitive, and if you don't need the grade requirements, you're likely to fall at the first hurdle sadly.

If you have applied and are awaiting offers (I don't know about ARU but Southampton haven't given out any offers yet this year) then good luck!