Apple is leading mobile and personal use technology right now, and Microsoft's attempt to enter the market is substandard, especially considering they are significantly behind competitors like Google and Samsung in the mobile market right now. They need to stick to where their competitive nature still applies - namely, desktop computer technology and gaming consoles.
Apple iPad has the history to be named the most popular surface whereas the Microsoft surface is not as well known and does can not offer the same. The iPad has branched out to offer many different cheap and common accessories and the Surface is just too new for it to be as mainstream.
I think that Apple iPad is more popular than Microsoft Surface, because Microsoft Surface is not very well know. Everyone has heard of Apple iPad. It is very popular. They sell very well. In fact, they sell so well that people line up to camp out so they can purchase them. That does not have happen for Microsoft Surface. They have some catching up to do.
I believe despite its higher price, the Apple iPad is favored over the Microsoft Surface or any other tablet for that manner. I think this is because of the easy to understand interface that is common in all Apple products. Unfortunately, I don't think Apple will be coming out with anything comparable in the future, so maybe Microsoft will surpass them in the future.
Apple products came out before Microsoft so people dont want to mess around figuring out a new product so they stick with what they know. Even though iPads are more expensive, people are more willing to spend that extra money for convience. Also, more people own Apple products so you can talk about it with other people.
The Apple iPad is most definitely the more popular tablet out of the two. More schools and people own iPads than own Surfaces. This is mainly due to people understanding how to use an ipad, the app store being stocked, and how they are readily available. Most people would rather get an iPad.