The best gym gear will depend largely on what you intend to do with your workout. A gym often offers a multitude of exercises, classes, and activities, and generally speaking, each one will require its own set of gym gear. Most exercises at a gym, however, will require a good pair of shoes, clothing that wicks moisture away from the body to control temperature, and a well-constructed gym bag to keep it all in. Remember, too, that your post-workout shower will require some shower shoes and a place to keep them after the shower, meaning the best gym gear includes more than just workout clothing.
Choose gym gear that will work for you, not for what works for others. If you spend a significant amount of time on the treadmill or stair climber, focus on choosing a good pair of shoes that will support your feet and promote good form. If you don't use the treadmill and instead work out in the weight room, think about choosing a comfortable pair of weight training gloves and clothing that will not interfere with the motions of the exercises. A swimmer will not need any of this equipment; instead, he or she should focus on a good swimsuit that is form-fitting, goggles that will resist fogging, and shower shoes for walking around the gym after your swim.
Moisture wicking materials are important for just about all gym activities. If possible, purchase gym gear that is made of materials that pull moisture away from the body to help regulate body temperature and improve comfort. Many shirts, sports bras, and other active tops will advertise whether or not they are moisture wicking, and while such clothing can cost a bit more than regular cotton shirts, the comfort factor is well worth the price.
Gym gear is not limited to workout gear. For your post-workout shower, choose a pair of shower shoes that are waterproof and quick drying. Shower shoes will protect you from any germs such as athlete's foot that may be lurking in locker rooms and showers, so choose a pair that you can clean easily every so often. Your gym bag should be large enough to carry all your gym gear but small enough to stow in a locker. Separate pockets will help you keep dirty clothes away from clean ones, and a separate pocket for your wet shower shoes is a handy way to make sure everything stays dry.