One consideration is an SSHD. These are hard drives that have an SSD-like cache in them. Basically the most frequently used content gets automatically cached to a small SSD, making load times for the same level or similar content decrease quite a lot.
The Seagate Firecuda drives are these and offer way better load times, which are *really* hard to take on PS3 after you game on a PS5 or XSX at all.
Looks like the 2TB Firecuda variant (which is what I have) is unfortunately quite expensive. If you care about this it may make more sense to get a cheap 1TB SSD instead depending on how many games you are playing at any given time. An SSD would probably massively improve install times for PS3 games, which are also awful. Maybe find some benchmarks and see what works best for your budget?
Here's an old video of the Firecuda load times comparison. It's pretty wild.