The biggest factor in the experience for a tablet PC is going to be the operating system. It is the basis for the whole experience including the interface gestures, application support and even what features a device can actually support. In particular, selecting a tablet with a specific operating system will essentially tie you to a specific platform just as if you selected a Windows or Mac based PC but even that is more flexible than the tablets are currently.
There are currently four major operating systems that are either available now for tablet PCs. Each of them has their own strength and weaknesses. Below, I will touch on each of them and why you may want to choose or avoid them.
Apple iOS - Many people will say that the iPad is a glorified iPod Touch or iPhone. In some ways they are right. The operating system is not very different between the iPad and the company's phone and media players. This has the advantage of making it one of the easiest of the tablets to pick up and use. Apple has done a superb job of creating a minimalist interface that is quick and easy to use. Since it has been on the market the longest, it also has the greatest number of applications available for it on the market. The downside is that you are locked into Apple's limited functionality. This includes limited multitasking and the ability to only load Apple approved applications unless you jailbreak your device.
Google Android - Google's operating system is probably the most complex of the options currently available. This has to do with the fragmentation of the operating system between the 2.x versions designed for smartphones and early tablets along with the 3.x version that is specific to tablet devices. The company's new unified 4.x version does correct many of these issues but some devices are still shipping with older versions. The greatest advantage that Android has is its openness. The downside is that the openness leads to security issues and interfaces that are not as standardized as some of the other operating systems. Android is also the basis for many other tablet companies devices such as the Amazon Kindle Fire and the Barnes and Noble Nook but they are heavily modified such that they aren't as open as the standard Android versions.
Microsoft Windows 8/RT - Microsoft has released Windows 8 which is their new all encompassing computing operating system for tablets, laptops and desktop. The release is a bit more complicated though as there will be two versions, one for traditional x86 that uses the standard OS and a special Windows RT for the more common ARM based tablet hardware. The ARM version of the OS will have more restrictions on it which may limit the functionality for many buyers.
BlackBerry Tablet OS (QNX) - Research In Motion was the king of early smartphones. They may have been late to the tablet market but they took an existing QNX based operating system to build their tablet specific operating system. It offers a very quick and streamlined experience and some superb video processing ability. One new feature even allows for cross compatibility with some Android 3 applications. The downside is that in their rush to get it to market, some key applications including mail and calender were noticeably absent at release but have been added in with the 2.0 release. It does have a nice tie in to those that might already have a BlackBerry phone.
WebOS - HP specifically purchased Palm for it's WebOS software platform that eventually made it into their TouchPad tablet. This turned into a huge problem for HP and the tablet was discontinued shortly after its release. HP recently sold off the operating system assets and rights to LG so it is possible that the operating system may come back in the future through LG branded devices.
Application stores are the primary means that consumers will be acquiring and even installing software onto their tablet PCs. This is something that should be considered before buying a tablet as the experience and software available to each has very specific implications to the tablet PC. In most cases, the application store for the device will be operated by the company that developed the operating system for the tablet. There are a couple of exceptions to this.
Those using an Android based device will have the choice of multiple application stores to use. There is the standard Google Play that is operated by Google. In addition to this, there are various application stores run by third parties including Amazon's Appstore for Android, various stores run by the hardware manufacturers of the devices and even third party stores. This is great for opening up competition in terms of pricing for applications but it can make it more difficult to find applications and can raise security concerns if you are not sure who is actually running the store.
Owners of the BlackBerry PlayBook now can run some Android applications with the version 2.0 software. This means that in addition to BlackBerry App World, the tablet will also be able to access select Android applications that have been certified. The applications have to be repackaged by the developer. It is possible to sideload applications as well but it isn't an easy process.
Even Microsoft has gotten into the application store business with its Microsoft Store. Note that with the new Windows 8 operating system, only applications that fully support the new Modern UI can be used on both traditional PCs and the Windows RT based tablets.
In each of the different operating systems, there will be links to the default application store for each of the devices.
Application Availability And Quality
With the development of the application stores, it has become extremely easy for developers to release their applications to the various tablet devices. This means that there are a large number of applications available on each of the different platforms. Now some platforms such as the Apple iOS store have a larger number because the tablet has been on the market longer while others are just getting off the ground. Because of this, Apple's iPad tends to get various applications first and some of them have not migrated to the other platforms yet.
The downside to the large number of applications available and the ease with which they can be published is the quality of the apps. For example, there are thousands of list applications available for the iPad. This makes sorting through the available options for which is the best quite difficult. Ratings and reviews on the stores and third party sites can help ease this but frankly it can be a major pain to find even basic applications on Apple's store. Thus, a device with fewer applications can also have some advantages.
The other problem is the quality of many of these applications. Pricing of applications can be very inexpensive or even free. Of course, just because something can be had for free or even $.99 doesn't mean that it is well made. Many of the programs have very limited features or are not updated to correct problems with new operating system updates. Many of the free applications are also ad driven that will have various levels of ads displayed to the user while they are in the applications.