If you're watching outside England the chances are you'll get C4 for all Test-matches except the second of the summer, and Sky for that second and all the ODIs.
If you're watching in England you get this for the live stuff, and highlights of everything on both.
Sky is Charles Colville, Bob Willis, Paul Allott, David Lloyd, David Gower, Ian Botham and sometimes some others, usually invitational commentators, Michael Holding being probably the most popular.
C4 is Richie Benaud, Mark Nicholas and Dermot Reeve, with Simon Hughes the analyst, Michael Atherton from 2002 onwards, Geoff Boycott from 2004 onwards, and sometimes Barry Richards, Ian Smith and Ian Bishop, usually depending on who's touring but not always.
TMS, the radio, meanwhile, is Peter Baxter, Jonathan Agnew, Christopher Martin-Jenkins, Henry Blofeld, Bill Frindall and sometimes invitational commentators. None of them have ever let me down and all are exceptional at their trade.