In today's smartphone market, android has the highest market share, while blackberry OS10 is struggling to get back to the competitive position it used to have when smartphones were just invented. In this perspective, Android must be much better than blackberry to have a much higher market share. However, after experience both systems, it is very hard to say one is definitely better that another. Hence, I am writing this review to show the advantage of each operating system and hope this will help you to make a more informed choice when picking your next phone. If you are already an android user, maybe you would give blackberry a try after this. The device running android 4.4.2 is a Samsung Galaxy note 2(N7105) while the device running OS 10.3 is a Blackberry Passport. The two systems come in to market at about the same time, hence it would be a fair match.
Above are pictures of the home pages. Android(first picture) definitely has more customization features. At the home page, you can add widget such as different clocks. Different android apps usually come with widget that you can choose to put on the home page. On the other hand, the OS10(second picture) is more like Apple's ios where icons just lined up neatly. It is very easy to use, but everybody's home page inevitably look similar.I must say, both systems are very smooth with reasonable hardware capability of the phone.
As shown in the first picture above, the control panel that can be pulled down from the top of the screen of the Blackberry OS10.3 only have numerous setting's feature such as wifi connection, airplane mode and so on. However, the android 4.4.2 have both control panel and also a quick view for all pending notifications. In this sense, it seems that the Android 4.4.2 is more integrated in a way that you can access to more with a simple gesture of pulling down from the top of the screen.
However, it does not mean that with Blackberry OS10.3 you cannot access your notifications as easily. In fact the Blackberry OS10 has a special feature called the hub(picture above). The Hub basically shows all of your notifications no matter its your text message, missed phone calls and whatsapp. Most conveniently, you can directly reply to these notifications in the hub with out opening the application itself. Most amazingly, there is a feature called Priority Hub with learns my habit, such as what kind of message I would view and reply first, these important messages for you would appear in the priority Hub.

I think that such a way to manage my notifications is more efficient than the Android way especially when there is a lot notifications pending.

The hub is open by a simple rightward swipe on the main screen at the home page. It can also be open through a upward then rightward swipe in any running applications. I would say it is as easy to use as the android notification center, but it is more powerful.
As for multitasking management, both systems are quite different. For the blackberry OS10.3, each running task is shown as small little box on the home page. One great feature of the Blackberry OS is that in the multitask page, the little box of each task would show a very short summery of your status on this task. For example the phone app, the small little box would show your recent activities of incoming and outgoing calls. I find such a feature very handy because it provide you most useful information even when the task is running in the background. Also, Blackberry OS allow 8 active background tasks, when the number of app you open exceed 8, it would close the left top small box of the smaller boxes. However, you can long press one task and move it forward, so that it is more prioritized and newly opened app would not close that task.
For the Android 4.4.2, the multitask window is just what it is, it arrange your recent tasks linearly. you can very easily kill any active task by swipe it sideways. However, you would not have the freedom to arrange the priority of the tasks like what you can do with the Blackberry OS10.3. Since there is not a limit on how many apps can run in the background, the android system can get very laggy if you do not kill background processes regularly.

Yet the android system have a single key locate at the bottom right corner of the screen with allow you to kill all processes at once, but for blackberry, you need to press the small little cross for each task individually.

Intriguingly, the two systems have one very big difference. Android system is still based on one physical home key to perform return to the home page function or light up the screen. However, Blackberry emphasize gesture by not having a physical home button.

This result in a very fundamental difference, for android, you would have a very short learning curve for using the phone, because you have a physical home button associated with visual back keys and menu keys. All of these are very direct and intuitive.

On the other hand, for blackberry OS10.3, you would need to first familiarize yourself with numerous gestures before you can use the phone as a daily driver. When I switch from android to blackberry, it took a while before I am used to the right swipe to open the Hub and a up swipe from the bottom of the screen to light the screen.

Furthermore, it is very obvious that the Blackberry OS10.3 is born for productive or business users. All the transition simulations in the system are extremely brief and short. Your every input would be reacted extremely fast with no time wasted.

Android is also not bad in this aspect. However, it is not as efficient and productive as blackbery.

As for ecosystem, the Android, I would say is the second best ecosystem in the market.(the best is Apple which do not have its close competitors yet.) The android market have apps, musics, books and movies. These resources are easily available with free content or with online payment. There are great many free apps that have very high quality. With the android market, I can find all I need, no matter its productivity apps or games. Most of the apps runs perfectly. However, since there are a great number of android phones in the market with different resolutions of the screen and different hardware capability, some apps may be running perfectly on one particularly model but not on another.

For blackberry OS 10.3, you can see that I opened two app stores, one is the blackberry world(first picture) and the other is Amazon app store(second picture). Blackberry has lone been criticized for the lack of app in the blackberry world. This time, the blackberry OS10.3 is compatible with android apps. And the system has a build in Amazon app store in place. This gives a much wide range of app choices for Blackberry OS10. You can directly install APK files too. For the blackberry world, there are great apps that are designed for blackberry. Hence,they are very responsive and very seldom break down. However, it have very small amount of apps. For example you cannot find youtube and weibo apps. Yet there are some third party substitute apps that may perform the same function. Another thing is that most good app in the blackberry app store are not free.
However, certain android apps are not perfectly running on the blackberry OS. Since each person have their different favorite apps, there would be some trial and error to find out whether your favorite Android app would run perfectly on the blackberry device.
(there is one more thing. If you live in china, Blackberry OS has a very huge advantage....Because in china, with the great firewall which black many foreign site, Google service is also blocked. this means that Google app store cannot be opened. Yet blackberry world and Amazon app store are allowed.)

In conclusion, both systems have there advantages and to many people's surprise, the Blackberry OS10 with have a bare less than two percent market share is actually not that bad. Its just that too many people are obsessed with the main stream operating systems such as android and Ios. With my comparison, I hope that people would have a more clear perspective that each system have its advantage in certain areas and the review would help you in making future decisions on which system would you stick to.