At the moment I am building a pc and was wondering if the brand of hard drive mattered or if it what was just the amount of space? Also do you have any recomendations for what are the best hard drives.
It all depends on what you want. Some brands are more reliable than others...but you also have to look at the specific models to see how reliable a particular model is. And what specs that model has.
I use the Toshiba ones for recording and editing videos and have used them a lot. Off the top of my head I have used them each to store at least 60 TB of data so far with no issues.