They're all good TBH... Maths is gonna be the hardest so put loads of focus into that, Economics and Psychology aren't that hard if you just follow along with the curriculum and go to every lesson. media on the other hand is a piece of cake from what I've heard, my friends didn't even attend half of their lessons and finished with at least a B.
How do these qualify you for good uni courses? I recommend the following:
Economics, Banking or Finance - These can get you jobs that make serious cheddar, thank your Maths and Economics
Events Management - Pretty enjoyable course so they say, employment is hit-or-miss and you need a bit of luck or connections
Psychology - Very common course so competition for a job is fierce, though if it's your passion then go for it
Primary/Secondary Education - A-level choices don't really matter so long as you get good grades
Mathematics - Only for the determined, if you finish with a 1st then your job prospects are endless
Computer Science - Saved the best for last, you won't get into Oxbridge cuz they demand Further Maths as well but you can still get into loads of good universities like Sheffield, Leeds, Manchester, Nottingham and the job market is exploding right now. I just graduated a Software Engineering course which is very similar (from a low-rank university) and I start my career on Monday, less than a month after I finished exams.
There are actually loads of options if you look around on UCAS search but these are the most well-known courses that I can think of