When choosing a cooling system for your computer upgrade, you should look for features that suit your needs and preferences. Compatibility is key; make sure the fans, heat sinks, and radiators fit in your case, the blocks match the sockets of your CPU and GPU, and the pump has enough power to run the loop. Additionally, consider the noise level of the cooling system, especially if you are sensitive to sound or use your computer for audio or video editing. Check the decibel rating of the fans, pump, and radiators and opt for quieter or adjustable speeds. Performance is also important; evaluate the heat dissipation capacity, airflow, and pressure of the cooling system. Consider the thermal design power (TDP) rating of the heat sinks or blocks and the cubic feet per minute (CFM) rating of the fans or radiators. Additionally, check for static pressure (SP) rating of the fans to determine how well they can push air through obstacles. Lastly, aesthetics should be taken into account; look for colors, shapes, and lighting of fans, heat sinks, blocks, and radiators that match your style and theme.