I started to think, "No, the Nexus One is..." but then realized that T-Mobile isn't necessarily the best network around, especially when compared to Verizon.
If you're a physical keyboard option fan, and want a decent processor, and a "stock" phone, the Droid is the best Android-based phone currently on the market. (Even if you're not a physical keyboard fan, the Droid is good... it's just that the physical keyboard makes it a bit thicker and heavier than other phones without one.)
In the past year or so, I've owned an iPhone 3G (AT&T), a Palm Pre (Sprint), and a Droid (VZW). While the iPhone had its good points (usability is one of them), I'm happiest with the Droid.