Because you really have no clue what you're talking about.
I have owned several android devices because I buy new ones when they come out and sell the old ones. Similarly, I have owned DOZENS of differently apple products.
I won't bother going into why android devices are unsuitable for anything except child's play, you would not be able to fathom the ability of stability, user interface, responsiveness, and application dominance in productivity setting. Needless to say, any business would be absolutely a fool to use anything but iPads over an android tablet.
You are either very thick or just lying. Why would you keep buying something you think is rubbish?
The funny thing is I have never said Andriod is better than iOS. I have owned 3 iPads and 0 Andriod tablets but I am aware that Andriods are more flexible than iOS much like Windows PCs are more flexible than Macs. It doesn't make them better.
You need to take a time out and stop sounding like a fanboy.
Edit: just read your edited reply, you've said that you use them for e-book readers. Can I suggest you stop buying hundreds of Andriods and buy a proper kindle?