There are a lot of good developers mentioned in this thread, but I think it is better to choose a popular film developer and a film or two that you like and then get to know them well rather than keeping on switching to different films and developers.
D-76/ID-11, Rodinal, Perceptol and Xtol etc are all very capable developers.
I'm not so sure about the one developer, one film suggestion.
I'm not suggesting that anyone should switch around without reason and I would say sticking with one combo while learning to use the tanks and timers makes sense, but unless we experiment some with the various options, we won't understand the differences between say TX and Delta 100 and 3200 and Pan F and TMax and ID11/D76 and WD2D+ and XTol.
Given that shooting film at box speed and following the manufacturers directions can provide really nice workable results. There isn't much of a downside unless you believe in magic bullets.
Mark Barendt, Beaverton, OR
"We do not see things the way they are. We see things the way we are." Anaïs Nin