Load times are a very SMALL part of the gaming experience.
As for MULTITASKING, you'd be best with an SSD for Windows if possible. If it's not in the budget, yes a single 1TB WD Black is a good drive (read my summary for my caveat though), however the 3TB Seagate is also a very good drive (as a second drive; 3TB is problematic as your ONLY drive).
My general recommendation for people goes like this:
128GB SSD (Windows and applications)
1TB or greater Hard Drive (STEAM GAMES, Windows drive backup, multimedia)
- I DOWNLOAD to my SSD then anything I keep I transfer to the large Hard Drive (Prevents hard drive having to constantly spin up when I'm on the net)
- I have all my games on a 3TB Seagate drive. This works very well. I have a "STEAM" folder and a separate "GAMES" folder for non-Steam games.
- If you have a Seagate or WD drive, you can get the free Acronis True Image software from their site (I think Seagate has it named differently)
*Make an initial backup that you always keep
- if you buy an SSD you can CLONE your existing OS to it.
- if you get an SSD, update the firmware
- the SEAGATE drive I mentioned also has newer firmware
- WD 1TB Black is fine, but maybe not best value
- Seagate 3TB drive is quite fast (don't forget that a Hard Drive is faster on the outer edge. If a 1TB is near full, the inner files are about HALF the performance as the outer; the 3TB is the same, however at 1TB usage performance is all still very high.)
- SSD (Windows/apps) + HDD (games, mass storage, backups)
- flash firmware on SSD (HDD if available)