There are various factors that drive employees to stay at a job rather than leave. Salary is no doubt a big one, but workplace benefits are often an equally important part of the picture.

As an employer, it pays to know what benefits workers feel they're lacking, because if you manage to become one of the few companies in your area to offer them, you might attract talent you otherwise wouldn't manage to entice -- while retaining the employees you've worked hard to train. These five benefits are ones that employees really want but currently don't have, according to office-supply company Zoro.

Smiling woman at laptop

IMAGE SOURCE: GETTY IMAGES.

1. Unlimited paid time off

Most companies offer some amount of paid time off to workers, but very few offer unlimited vacation. If you want to set your business apart from the pack, it pays to consider letting employees take time off as they choose. The great thing about a limitless time off policy is that it encourages accountability -- employees are responsible for making sure their work gets done, and that their time away doesn't hurt their productivity. Incidentally, you might find that your employees wind up taking less time off, not more, once you switch over to an unlimited vacation policy. But your workers (or potential workers) will appreciate having the option to take time off as they please, which could boost their enthusiasm for the job.

2. Four-day workweeks

Workers today crave flexibility more than many other things, and achieving a decent work-life balance is high on their priorities list, too. That's why so many employees would relish a four-day workweek. If the nature of your business allows it and you're willing to give it a go, you might find that your workers are more productive knowing that they have less time at the office to get things done. Just as importantly, you'll send the message that you respect the fact that your employees have lives outside the office.

3. Company-paid vision insurance

Not every employer offers vision insurance, but if you're willing to provide that benefit, your eyeglass- and contact lens-wearing workers will have something to celebrate. While most health insurance plans will cover eye diseases or injuries, they won't pick up the tab for routine vision checks, glasses, or contacts. Once they have vision insurance, your employees will have one less expense to worry about.

4. Company-paid dental insurance

Dental insurance isn't always a given, but if you don't provide it, you could wind up leaving your employees on the hook for some pretty hefty bills. The average cost for a regular dental cleaning is anywhere from $75 to $200, depending on where you live. Meanwhile, the average cavity filling costs $90 to $250. By providing dental insurance, you'll help your employees maintain good oral health and avoid absorbing the cost of dental care on their own.

5. Company-paid medical insurance

You'd think health insurance would be a given in this day and age, but many companies skimp on healthcare in different ways. Some offer lousy plans with limited coverage and expensive deductibles and co-pays. Others are stingy when it comes to subsidizing premiums, leaving employees to pay more out of pocket for coverage itself. If you want to attract and retain talent, aim to offer a comprehensive health plan and pay the premiums in full. It's a good way to let your workers know that you have their well-being in mind.

In today's competitive job market, every business needs an edge. Focus on the benefits employees feel they're lacking, and you'll likely have an easier time filling open positions while keeping existing workers happy.