Mountain View, California, is one happy town, at least from 9 to 5.

Today, Glassdoor revealed its annual list of "50 Best Places to Work," with Google claiming the top spot. Google has made the Glassdoor rankings every year since the list's inception in 2007, climbing steadily up the charts. This year, however, Google made a considerable jump from last year's No. 8 spot.

"Google employees are now more vocal, reviewing the company at a higher rate this year," Glassdoor career trends analyst Scott Dobroski tells Inc. So what's behind the recent increase of passion among Google employees? It's not tied directly to how much money they make. Here are five reasons, taken directly from Google employee feedback submitted to Glassdoor:

1. Work that matters

Google employees are motivated by the fact that they believe their work has a positive impact on the lives of others, according to Dobroski. 

"My work is used by lots and lots of users," wrote a Google developer advocate working in the Mountain View headquarters. "It's cool stuff that makes people happy."

2. Benefits for families

Dobroski says that a noticeable new theme in this year's Google reviews is the extension of paid paternity leave from seven to 12 weeks. New dads and adoptive parents working at Google can now take up to 12 weeks of paid paternity leave, while moms continue to be entitled to 22 weeks.

"Not only is the policy generous, but the atmosphere at Google is such that you can take the full leave and not hurt your career," wrote a Google employee on Glassdoor.

3. "Genius" co-workers

Another reason Google employees love their jobs is that they get to work with "genius" co-workers, Dobroski says, quoting a Glassdoor reviewer.

"The company attracts some of the best talent and best people to work with in the world, which is the most important bit," wrote a San Francisco-based Google program manager.

4. Smart perks

Google practically invented the concept of sweet office perks, which now extend even after an employee dies. From the on-site doctors and haircutters to the gourmet cafeteria food, every perk at Google has a calculated reason, designed to keep employees satisfied. This applies to how long employees should wait in line during lunch (three to four minutes, ideally) as well as how much paid maternity leave they receive.

5. Unparalleled career opportunities

"Opportunities for career growth, and tons of career development resources available," wrote a Google strategic partner development manager in Mountain View.

Even if employees decide to leave the Googleplex, having Google on their résumé has never hurt anyone's job prospects, regardless of career path or chosen profession.