I will always design for, and use, the most prevalent and used platform out there, and that just happens to be, Windows and the whole Windows ecosystem
I can understand the "design for" logic. On mobile, that would be Android and iOS. A guy who has suffered a horrible band saw accident could probably still count the Windows percentage of market share on one hand, and that market share is about to disappear since Windows 7 is now officially an orphan, no reason whatsoever to buy it.
But as far as the "use" logic, then if you wanted the most popular vehicle you'd have to buy a Ford F-series truck, even if you just wanted a car. If you wanted the most popular car you'd have to get a Toyota Camry. Yuck. Why?
With 90-95% of the PC market, I would say that, the biggest platform for usage, right now, is the Windows platform, and Apple’s Macs are a very distant second. I wouldn’t use the car analogy for comparing the computer market, since, the Windows auto equivalent would have to include the Toyotas and the Nissans and the Subarus and the Fords and the Chevys and the GMs and the Hyundais and the Hondas and the VWs and the Chryslers and just about every other manufacturer out there, while, the Apple line would probably be the BMW and perhaps a couple of other Luxury makes. Remember that, Windows computers come from many different manufacturers. While Apple may be making loads of money from their lineup, their market share of computers is tiny in comparison to Windows.
When it comes to smartphones and tablets, I wouldn’t target any one of them, since, it’s such a volatile market, and, what’s up today, could just as easily be down tomorrow, and it’s going to be years before that market settles and we learn who the winners and loser end up being. A generic design, if at all possible, is what I would prefer, and then just try to tweak for the different platforms. My preferred approach is to “write once, run anywhere”.
When it comes to the Windows phone market, it would be very foolish for anyone to discount the Microsoft entry, since, they’ve been known to come from behind and take over any market they insist is theirs to own, like they did with the XBox and the Office software market, and which they also did with computer OSes, and with web browsers. I can see WP8 being a major player within 2 years, and perhaps taking the lead shortly thereafter. They’ve got the resources to compete better than any other company, and that includes Apple and Google, since, Microsoft has the biggest development staff, and the widest variety of experience. That’s not to sound fanboyish, but, more on the practical side. However, like I said, I wouldn’t be targeting any single platform. And, btw, when it comes to the UI, that’s where your suggestions for breaking up the criteria screen would be most helpful, since those smartphone screens wouldn’t be able to accommodate so much data and so many boxes.