HGST has long been the gold standard. And HGST is now WD. For a while, actually. I bought a WD Gold drive in 2019 that actually turned out to be HGST.
Yes, but just because they merged, doesn't mean WD will automatically get better, or even that HGST will continue to be as good. It's not unknown, or even all that uncommon, for a brand to get worse after being acquired. That said, I don't disagree about HGST/WD being good drives, I just disagree that Seagates are trash or even
significantly worse, on the average. They've had their bad models, but so have the others. Based on the evidence I've seen, I feel they are close enough that people should just go with whichever is the better value. I just recommend against buying direct from WD due to packaging issues, and try not to buy multiple drives at the same time from the same vendor, since if that batch has issues, all your drives will be affected and may die early. If you do buy multiples together, you should do so in pairs from different vendors and/or at different times, and pair them up for backups, so one drive from one batch will be backed up to another drive from a different batch. Or if doing RAID, mix them up so your whole RAID doesn't die within days. BTW, I seem to recall when researching drives a few months back that the Golds typically are HGST.
For SSDs, I'd say Samsung, WD, and SK are all top-tier, and you can't go wrong with any of them (generally speaking; there's always going to be a bad drive here and there). But WD tends to be the most expensive, Samsung has issues with not getting the drive ordered, and SK is the most efficient (best for laptops) and cheapest. But most people don't need crazy speeds, and with backups, which should be done regardless of brand, reliability isn't necessarily a huge factor, so even a cheap SSD from someone like TeamGroup (just an example, don't take as an endorsement of the brand) is fine for many people. If all you're using it for is to hold games that can be redownloaded if the drive fails, or as a drive for temporary storage of active downloads or something else where the data isn't important, then reliability isn't really a concern.