When choosing a TAA type 3 pole UK plug insert, there are several factors you should consider:

1. Compatibility: Ensure that the plug insert is compatible with the device or equipment you plan to use it with. Check the device's specifications to determine the appropriate type of plug insert needed.

2. Voltage and current rating: Check the voltage and current rating of the plug insert to ensure that it can safely handle the electrical load of the device or equipment.

3. Number of poles: The TAA type 3 pole UK plug insert has three poles, so ensure that it is suitable for the device or equipment that requires this configuration.
   

4. Material: The plug insert should be made of high-quality materials that are durable and can withstand frequent use.

5. Certification: Look for plug inserts that are certified by appropriate regulatory bodies to ensure they meet safety and quality standards.

6. Brand reputation: Choose a reputable brand that produces high-quality plug inserts and has a good track record in the industry.

7. Price: Compare prices of different models and choose one that fits your budget.

Overall, when choosing a TAA type 3 pole UK plug insert, it is important to consider compatibility, voltage and current rating, number of poles, material, certification, brand reputation, and price. By taking these factors into account, you can select a plug insert that is suitable for your needs and provides reliable performance. It is recommended to consult with a qualified electrician or technician if you are unsure about the appropriate plug insert for your device or equipment.