I'm on the hunt for a phone but will be waiting a few months before I make a decision on which smartphone to buy. A couple of the Android phones look very pretty - and useful. iPhone has been (and still is) the standard and will make my shortlist. I've almost ruled any Symbian phone off my list now. I really like what I've seen about the Windows Phone 7.
If I had to make my choice in the next 6 weeks, WP7 phone would win mainly due to its Office, Zune, and Live integration - but the hardware is rather important too. That said, I'm not committed to any new phone hardware or OS so I might just hang onto my 4-year-old hand-me-down Moto Razor as long as it continues to work.
I have my rooted Droid overclocked to 1Ghz (which is twice as fast as a stock Droid). All my apps run smooth as silk.