Two directions: Android and iOS.
One is about choice and power. One is about marketing and hype.
iOS gives you the former: far greater choice of apps, far greater choice of quality apps. You can do more with iOS, and no amount of imaginary "choice" is going to let you do those things with Android.
Whereas Android is driven by marketing: using buzzwords like "open source," and carefully-cherry-picked spec numbers, and big screens that look nice on a store shelf (which is all that matters for getting your money). Just like the TV with the brightest colors sells best of the shelf--not the one with the most accurate color.
Android marketing forgets (intentionally) that what matters is what a device can DO, and how well and how easily it can do it. Specs mean nothing except what they let you do. And apps, not specs, are how you do everything.
Please make us a list of Android-only killer apps--not little utilities, but real serious apps, like ArtRage, GarageBand, Procreate, Inkpad, Pages, Numbers, iMovie, Keynote, Textastic, iDraw, iTunes U, OmniGraffle, iPhoto, Bento, Omni Outliner, ArtStudio, NanoStudio, Diet Coda, Intaglio, Freeform, TouchUp, iTeleport, ReBirth. Where are apps like these for Android? Not, “well, here’s SOME kind of app for this,” but a truly top-level (and tablet-optimized) experience with that level of productivity? I can think of only two candidates: Photoshop Touch and possibly Sketchbook (which is reportedly maddeningly slow on Android). A few others surely exist too, but can they equal the scope and selection I’ve listed—which in fact only scratches the surface on iOS? And those two ARE on iOS. Where are the great Android-only apps? Just some little utilities, as near as I can tell, and iOS has tons of exclusives in that category too.