Look when I tell you this, you are going to think I am insane. My favorite upgrade by far to my super budget PC is throwing a SATA SSD drive in there and installing a fresh set of windows. Watching those boot times were so satisfying compared to my old HDD.
This is just an example, however, NVME M.2 drives are widely popular with even better RW Speeds. That is my next upgrade and it is totally worth the switch