This topic has been covered to death many times. Nothing has changed.
External enclosures are a crapshoot because you don't usually know what drive is in the enclosure. It can vary wildly. They are a good way for companies to get rid of old stock.
Each drive is different. And I mean *EACH* drive, not model. It takes over 40 hours of testing for me to qualify a new drive, and they fail fairly often. Even then, an early failure is still a possibility.
It's all about your workflow and how you manage those drives: backup, monitor, test. Learn how to use SMART. Never leave yourself with only one copy. Accept that silent data corruption DOES happen, and plan for it.
External drives are a target for theft. DVDs are clunky, but less likely to get stolen. I think they can still have a place in a backup strategy.
1TB is still the sweet spot. Capacities higher than that have new tech that is still very much bleeding edge - especially in the consumer drive market. Basically, the drive arms have another sub arm at the tip that moves. That is the current tech direction, but it is still very new. Another (old) approach is to pack more platters in the drive, and that has serious drawbacks.
Some larger (2tb) drives have timers to park the heads when not in use. That isn't necessarily just inconvenience or power saving, it can be a sign that the mechanism isn't very robust.
I'd love to buy 2TB drives, but I just don't see the tech as mature yet.
Seagate has been flirting with bankruptcy for years. I'd avoid them. The western digital black drives have always been good to me. Basically an enterprise drive priced for the consumer market.