The Lenovo ThinkPad Yoga 15 and 12, and the Fujitsu LifeBook T935 are convertible tablets. The Wacom Companion 2 is not a convertible tablet, but it's a device aimed at developers. Of the mentioned systems the Yoga 15 is the most popular on Google Trends. These systems are aimed, I'm assuming, to developers.
The Apple iPad and the Microsoft Surface Pro 3 are aimed at mainstream users. On the chart above you can see that the Surface Pro 3 is barely on Google Trends when compared to the iPad. You might have not noticed but the Yoga 11 is also on the chart--so incredibly low.