Closest I came to being able to replace my laptop was with the surface RT tablet. That's because surface comes with a full version of Microsoft Office. You can use other applications for Android like Kingsoft, QuickOffice and Polaris to edit the content of a document but you can't edit any special fields. for work I need to edit info fields like the date last revised, revision number, department, and anything that is considered an info field. mobile applications to edit photos and video are very rudimentary in Mobile OS. you get some set filters, can add text overlays, and some cropping or preset resizing filters. With video for you can edit out certain chunks, splice together some video, and add some transitions, but you can't do any sophisticated particle overlays.
I will say there is more support for cloud computing in android than there is in Surface RT right now. There's no drop box app for Surface for instance.
if you want to use a tablet as a laptop replacement, go with one that has a keyboard dock such as the Asus transformer line. You will be able to do most of a laptop's functions as long as it's all Internet based. that means blogging, photo uploading, web apps coded in HTML5. You can then remote into a laptop and use the full desktop OS if you need to be able to access programs for flash, etc.
I avoid iOS for anything other than media consumption because of the limits in accessing the file system. If I want to get any work done I absolutely need to drag and drop files. right now Android has the advantage over Windows 8 because of app development. But the way each operating system works is very similar. This time next year we'll have a real choice between an Android verses a Windows tablet as a true laptop replacement. the main advantage to Android is that the operating system is the same across all form factors of devices. A 4.5 inch phone works the same as a 7 inch tablet and a 10 inch tablet. Add a keyboard and USB port and you have a mobile laptop.