SSD is set as the boot drive. I don't have any choices now, I just have this 1TB hard drive or I have nowhere to install these games to. I'm looking forward to buy an internal HDD, maybe a WD Red or Black 2TB
Well, get an internal hard drive, as that is your best option, as installing games on external drives is not the greatest idea, as they are not exactly designed to be constantly having something running off of it. They are more designed for being used as backup or just file storage. So, get a WD black (your choice of capacity). If you wan more storage and don't mind waiting logner for it to load, get a massive WD green drive for the same money you would spend on a smaller capactiy WB black.