If you must have… an Android - Verizon
Android phones are a tricky thing, because makers like Samsung and HTC have a bad habit of repackaging the same phone with a different name for different carriers. For example, Verizon's HTC Thunderbolt, AT&T's HTC Inspire and Sprint's Evo 4G are all virtually the same phone with only minor differences.
All told, Verizon has 19 Android phones, including three 4G models. They range in price from free to $299.99, with the 4G phones all over $200.
AT&T has 13 phones, all but two are under $99. The two pricier phones are both 4G phones, the HTC Inspire 4G and Motorola Atrix, which AT&T is only just beginning to roll out. Most of the phones are lower-end models with less memory, smaller, lower resolution screens and slower CPUs.
Sprint has 11 Android phones, five of which are 4G phones. It has the cheapest of the 4G phones, the EVO 4G, and the rest of the phones are under $200. Some of them, like the Kyocera Echo and Motorola XPRT, aren't exactly top of the line, so it's a high/low game of quality.
T-Mobile has 10 Android phones, although it has multiple versions of the same model. There are three different MyTouch 4G phones, for example, only differentiated by color. Later this month it will get an exclusive release of the HTC Launch 4G, a beautiful phone with a large screen and fast processor, that will be competitive with the top-end offerings of the other players.