In my opinion, baby gyms are very popular toy that can serve the mentioned purpose and can encourage your baby's development; colors, shapes and sounds. Besides, baby gyms can also provide your baby a fun time as well.
The following items are my suggestion for best baby gyms that can encourage your baby's development.
1) Baby Einstein Neptune Ocean Adventure Gym
2) Lamaze Space Symphony Motion Gym
3) Bright Starts Petals and Friends Activity Gym
4) Fisher-Price Rainforest Melodies and Lights Deluxe Gym
5) Tiny Love Gymini Monkey Island Activity GymBaby Play Mats)
I can guarantee you that these are best baby gyms that can encourage your baby's development indeed. Good luck.