After Apple, Samsung and Google, another company is now rumored to be building a smart watch: South Korea's electronics giant LG.

According to Korea Times, citing a source familiar with the matter, LG is building both a smart watch and a product similar to Google Glass."The company has spared no efforts to invest in products that it believes are must-haves to stay ahead technology wise in the market, whatever the situation may be," the source said.

Of course, details about the devices are lacking, which means we now have not one but four "upcoming" smart watches, and absolutely nothing is known about any of them.It's possible these companies consider the smart watch the next big thing. Remember some of these companies, namely LG, have built a phone-watch hybrid (pictured above) before.

However, we're more inclined to believe that nowadays, no major consumer electronics manufacturer wants to be left behind on a new product category, even while we're still deep in rumor territory.Which company — Apple, Samsung, Google or LG — is most likely to build a smart watch you'd actually want to use? Share your thoughts in the comments.