I would say the #1 thing would be good management/valuing employees.
My husband works as a Widget Maker. He has pretty much the most plush job a Widget Maker can have. It's with a large company, so he has plenty of work; he gets paid per hour rather than per widget; he has good benefits and great pay for his field; he has optional overtime which pays extremely well; and he has opportunity for advancement. 90% of Widget Makers are not so lucky.
And yet, his experience at this job has been hell because of a bad boss. He is constantly berated, told that his productivity--while well above average--is not good enough, told that he is worthless and replaceable, and literally screamed at for any and every minor infraction. His boss has never had any formal management training and seems to think that intimidation is the best tactic. It's no wonder that, despite the plushness of his job, his location has very high turnover.
The worst part is that he's spent years looking for a job in his field that pays near his current salary and offers benefits, to no avail.
(Thankfully, a transfer is in the works and we will likely be relocating soon!)