There are a few factors to consider when choosing speaker drivers. Here are some things to consider:

1. Size: Speaker drivers come in a range of sizes, and the size you choose will depend on the size of your speaker enclosure and the frequency range you want to produce. In general, larger drivers are better at producing lower frequencies, while smaller drivers are better at producing higher frequencies.
2. Power handling: Make sure to choose a driver that can handle the power output of your amplifier. If the driver is not capable of handling the power, it may fail or produce distorted sound.
3. Frequency range: Choose a driver that is capable of producing the frequency range you want. For example, if you want to build a subwoofer, you will need a driver that is capable of producing very low frequencies.
4. Sensitivity: The sensitivity of a speaker driver refers to how efficiently it converts power into sound. A driver with high sensitivity will produce more sound for a given amount of power, while a driver with low sensitivity will require more power to produce the same amount of sound.
5. Impedance: The impedance of a speaker driver refers to the electrical resistance of the voice coil. It is important to match the impedance of the driver to the amplifier to ensure that the amplifier is able to deliver its full power to the driver.
6. Brand and model: There are many different brands and models of speaker drivers available, each with its own unique characteristics. Do some research and read reviews to find a driver that is well-regarded and will suit your needs.