It really depends on your usage. People can debate the nature of "closed" and "open" operating systems, but you'll be spending more of your time in the apps than playing with the OS. iOS may not allow you to easily do things like placing files onto the device, but there are apps that give you file management capabilities (see Documents, a free app by Readdle; there are probably others like it).
As far as reading and web browsing go, both devices will be pretty equal. If you're looking at a device like the Nexus, reviews tend to ding points for the screen aspect ratio compared to the iPads. It's a matter of personal preference. The writing capabilities of Samsung's Note line are quite nice, but if you won't be using your device primarily for those purposes then it doesn't matter. Photography-wise, it again depends on the apps. I know there are a few photo management and editing apps for iOS, but I don't know what's available for Android. In my opinion as a hobbyist photographer, I wouldn't expect to do any serious editing on these devices.
Other than that, you need to look into other benefits. For example, you have an Android phone. There's something to be said for having two mobile devices on the same operating system so that you can share apps between them. It's also an OS that is known to you. I don't know if there are other interoperable Android features.
Personally, I use a retina iPad Mini at work and have no desire to use an Android tablet. Some colleagues of mine use Android tablets (I believe they're Nexuses, some the old and some the newer 2013 version), and it seems like they run low on battery fairly frequently. Their devices also occasionally have trouble locking on to the wireless network. The retina Mini has no such problems. Additionally, many members of our team use iPhones. The ability to respond to iMessage texts through the iPad that is already on and in my hands, without having to pull out my phone, is quite a boon. That benefit is lost when working with team members who don't use iPhones, of course.
Basically, you need to look at the apps that you would be using, and also consider whether the differences in hardware really make a difference to you. Better battery life and lighter weight mean nothing if the device will largely be used at a desk near a power outlet, but by the same token, a pen and greater customizability are meaningless if you don't intend to write or tinker.
This is what I am now. Never had a tablet before. A friend gave me a Samsung Ace II X phone he had for free after renewing his "vows" to phone company. He hates smartphones so the small white thing is with me now. Since I never had an iPhone or iPad, I just can say it's working flawlessly. Got used to Android 4.0. Guess what: now I'm craving for a tablet and...all my friends have Samsung Note or Tab. Reviews and comparisons on the Web point in the same direction: you decide between the opened system Android or the closed one iOS. Between a 3 star construction and a 5 stars (Apple). Learn to let go of the extra SD card, the mini USB port, the Widgets and the Sylus pen. All arguments my friends have. I have a late 2012 27 iMac. In a nutshell and straight talk only, what will the 200$ premium for a 32 Gig iPad Air will buy me? I'm no gamer, no SMS maniac, no YouTube and Netflix addict. Apple or Samsung, I would mostly browse the Web, read papers and do photo stuff since I'm a semi-pro photographer. Don't judge: I really don't know what to do. Extra storage and S-Pen are a bonus. 
