Tablets for Reading Comics?

Recently, I've taken up reading comic books, and while I love the feel of physical trades and single issues, from what I've seen of Comixology on iPhone and on my brother's iPad 3, I'm in love. Plus, the weekly emails that Comixology sens me just makes me want to throw my money at them, but I can't buy comics in good heart knowing that I'll only read them on an iPhone 5. This is one of the primary reasons (along with some gaming, reading books and magazines, and web browsing) that I want a tablet.

I'm heavily invested in the Apple ecosystem (bought an iPod 4 years ago and spent a lot on iTunes, but now I'm a Spotify Premium subscriber, so that doesn't really affect me), to the point where between my brother and me, we've probably spent several hundred dollars on apps. So my question is whether or not the extra money for an iPad vs. competing tablets is worth the investment.

I have a Nook SimpleTouch for reading, so a Kindle is pretty much out of the question, because I'm not going to buy a Kindle if I have a Nook. I love Amazon, but I just won't do it.

I'm pretty sure I want a full size tablet, but the much smaller price tag of a 7" is very attractive to me as a high school student (if I get an iPad 4, my parents will pay for half as my only Christmas present, as they will with basically any cheaper tablet).

This is mainly what I'm looking at:

iPad Mini

-$329 for an 8" tablet seems steep, and the lack of a Retina display really hurts it for me, as does the A5 which I'm not sure will retain usefulness for much longer in the gaming realm.

Nexus 7

-$199 looks sweet, and I'm kind of interested in Android as a platform, but I'm still not sure about the app ecosystem.

Nook HD or Nook HD+

-Just because I'm a Nook user for reading, and those displays sound killer, but reading the Verge's review of the HD kind of soiled me on this.

Nexus 10

-$100 less than an iPad, and like I said with the N7, I'm interested in Android as a platform. Plus, that display sounds SIIIIIIIIIIIIICK.

iPad 4

-The big daddy of tablets. Does all of the bells and whistles of the iPad and its connectivity with the iPhone justify the higher price tag? That's really what I'm trying to figure out.