comoron: Right now, there's no dispute that Sprint has the fastest wireless broadband network. It's just a technical fact of life. Verizon will be bringing theirs online over the course of the next couple years, but most major metro areas will be covered by the end of this year. AT
&T will be a bit further out, as will T.Mobile.
Also, you asked about Virgin, but there are really only a few carriers in the US of national significance: Verizon Wireless, Sprint, T.Mobile, AT
&T, Leap, and US Cellular. Sprint owns or controls Virgin, Boost, Helio, Nextel, Assurance, Clear, and Clearwire. Leap owns Cricket and Jump. Verizon owns Alltel (rapidly being subsumed into the parent brand.) AT
&T owns Centennial. América Móvil/TelMex owns TracFone. U.S. Cellular and T.Mobile use only one brand.
The remainder are bit players of minor significance, particularly when it comes to brandband and/or national coverage.
When they call the roll in the Senate, the Senators do not know whether to answer 'Present' or 'Not guilty.' -Theodore Roosevelt