Any 10+inch color LCD display of 250dpi or higher works well for comic books. It turns out that if you make a tablet capable of showing HD video at 60fps, it can show you comic book pages quite well.

I use an Amazon Kindle Fire Ow It Burns HD10 for this, because it's at the minimum intersection of suitable hardware and price.

I think the Kindle Fire makes you jump through hoops to get apps via the Google Play store though and as I understand it, you need to do that in order to get Marvel Unlimited on there, which is something many people really want to have on their comics-reading device.

I think I rooted that sucker before installing everything I wanted. I don't think it's a suitable device for everyone.

You'll probably want to avoid any apps from Google Play anyway...