Should I use an accelerometer or gyroscope in my project? A friend and I are working on a sign language translation glove.

Our glove currently successfully uses 5 flex sensors to determine the bend of each finger and can accurately detect letters in the sign language alphabet.

We are now trying to add the functionality to detect one-handed words. Many of these words involve making a letter, but adding some motion. For example, the colour "blue" involves making a B, then shaking/waving your hand in the B position.

We are wondering which type of sensor would be able to handle this. From our research so far, we assume this will either be an accelerometer or a gyroscope, but are not sure which one would be best in the scope of our project.

Any help would be much appreciated!
An accelerometer is a better choice here. For your application, you aren't worried about initial motion but just acceleration. Plus, an accelerometer is cheaper.