Ive had good luck with used enterprise hdds. They are loud but have always worked fine. I like buying them all at once from the same seller, but I've mixed and matched as well.
I personally don't think smart errors are the end of the world either. A few of them on something large like 14tb isn't the end of the world. I've had more issues with brand new seagate 8tb than anything I've gotten used.
Ive had good luck with used enterprise hdds. They are loud but have always worked fine. I like buying them all at once from the same seller, but I've mixed and matched as well.
I personally don't think smart errors are the end of the world either. A few of them on something large like 14tb isn't the end of the world. I've had more issues with brand new seagate 8tb than anything I've gotten used.