A lot depends on who and what you are targeting. If eyeballs and advertising is what you after supporting Android is a must. But if you are after in-app purchases as your revenue model, it's iOS you want.
I've been developing mobile apps since 2009. Early on I was making as much off ad revenue vs app purchases, but by last year the ad revenue went in the crapper. So much so that I stopped releasing updates for android. By that time Android accounted for a little over 60% of the installs. It accounted for less than 15% of my revenues. Android accounted for over 90% of my complaints and requests for support because someone with a cheap pay-as-you-go android phone would run into a problem on a device I didn't even know existed. I was making at most a couple thousand a month from the apps, mostly from iOS users. It was enough that it paid my basic living expenses like rent & utilities meaning my day job work could go into savings. But it wasn't enough for me to go out and buy every freaking handset on the market at $600 a pop.
Now on the professional day job part of the world we usually price for iOS first and includes QA for current generation and usually the previous 2 generations before that. Right now if you paid us to write an app, we'd ensure compatibility with the iPhone 4, 4s, 5 & iPad 2, Retina, Mini. Next month it will likely be 5S/C, 5, 4S & iPad Retina, Mini, + whatever is announced next week.
For Android we will test against Nexus Phone & Tablet and certify QA with those devices only and it costs our clients about 1.5xiOS. Why? Because we know we'll be answering "QA for XYZ handset was not covered in the contract" a few times. So we build it into the price of the contract. We do offer QA for additional handsets & tablets @ $5,000 per Android handset/tablet. Most of our clients will maybe ask for QA against the latest Samsung Galaxy devices and that's it. Only one that I can think of asked for Samsung & Motorola because the boss man had a motorola phone.
When Android first started we tried to QA against as many handsets as we could and we were losing money on those contracts. When Google released their official devices we decided, even though nobody used them in the mass market, those would be what we'd test against. That was the "official" devices for compatibility. What handset makers & carriers did beyond that we'd have to charge extra to fix because we'd run into the same model android phone would have odd quirks between different carriers sometimes.