More so than for any other input device, the "best" game controller is a matter of personal preference. If it feels right to you, it probably is right. If it feels wrong, it's probably wrong, no matter how much someone else may like it. Use the following guidelines when choosing a game controller:
Make sure the game controller type is appropriate for the games you play most often. If you frequently play two or more games that are ill-suited to using the same controller, buy two or more controllers, and use the type most suited to whatever game you play. We make some suggestions as to appropriate types on the web site listed in Section 21.6.
All current game controllers worth having are digital models, although some analog models are still available. Note that some digital controllers use the analog gameport interface, including some high-end models. Digital gameport models are acceptable, but fully digital (USB) models are easier to swap in and out if you use multiple controllers. The only time it makes sense to use an analog controller is for games that run only under DOS or older Windows versions that do not support digital controllers, or if your system does not have USB ports and your gameport does not support digital controllers. Of course, you're unlikely to be playing games on such an antique system.
If you buy a model that connects to the gameport, verify that that controller is compatible with your gameport. Incompatibilities between PCI audio cards and digital game controllers are very common.
If an appropriate force-feedback model is available and is within your budget, buy it rather than the cheaper model. More and more games support force feedback every month, and that support is of a higher quality with each upgrade of many games.
Friends are among the best sources of information about game controllers. You'll get a great deal of feedback from them, much of it conflicting, but valuable nonetheless. Not the least advantage of this method is that they'll probably let you play a few games with their controllers, giving you the opportunity to judge the merits for yourself in a realistic environment.