It is difficult to say which brand of residential air conditioning has the best warranty, as the terms of warranties can vary significantly between different brands and models. That being said, here are a few factors to consider when looking for a residential air conditioning system with a strong warranty:

1. Length of the warranty: Look for a brand that offers a long warranty period. This can help to provide additional protection in case of any issues with the equipment.
2. Coverage: Consider the level of coverage offered by the warranty. Look for a warranty that covers a wide range of components and issues, including the compressor, the evaporator, and the condenser.
3. Transferability: Some warranties are transferable, which means that they can be transferred to a new owner if the property is sold. This can be a valuable feature, as it can help to increase the value of the property.
4. Exclusions: Be sure to read the fine print of the warranty to understand any exclusions or limitations. This will help you to understand what is and is not covered by the warranty.

By considering these factors, you can help to ensure that you select a residential air conditioning system with a strong and comprehensive warranty. It is always a good idea to do your research and compare the warranties offered by different brands to find the one that best meets your needs.