should i buy a corsair air 540 or a corsair 500r mid tower
it depends all on you. If you want better airflow and a compact case, go for the air 540. The 500r will be easier to build as it has more space compared to the air540.
So, if you are a PC building noob (like me) go for the 500r. Or, if you're a pro or want a compact pc, go for the air 540