What were your previous specs? And budget for this new one?
Terraria Community Forums
Vaikyia
Leinfors
Solid State Drive if you weren't already planning one. Best visible performance increase on my most recent PC out of every part I purchased.
The Ice Cube
For storage I recommend having an SSD along with a hard drive. If you are building a PC mostly for gaming, you can install Windows along with important programs you need on the SSD (250 GB would be enough), and then all of your games on the hard drive (I have a 1TB hard drive, you can get a 2TB one as well).
The Ice Cube
If everything you need will be installed only on one hard drive, your computer will run slowly, so having an SSD for all the important stuff and a hard drive for just games and whatnot is recommended.