The refrigerant of choice for manufacturers that manufacture residential systems is R-410A. This goes by different trademarks for different HVAC brands, but if you look at the details, you will see the R-410A specification.
The older R-22 refrigerant is considered by experts to be dangerous to the ozone layer. With this a production cap was implemented on R-22 in 1996, as it is being phased out along with all other ozone depleting chemicals. This phase out will affect supply and demand resulting in significant price hikes for the R-22 refrigerant. By selecting an air conditioner that uses R-410A you are protecting your investment by avoiding a product that is destined to become obsolete.
R-410A systems also use newer synthetic oils to lubricate the unit which out perform the "mineral oil" used in older R-22 systems. As air conditioners are built around the R-410A standard, they are able to implement smaller compressors that are quieter and vibrate less which reduces "wear and tear" over time. Additionally, R-410A absorbs and releases heat more efficiently than R-22 resulting in compressors less likely to burnout due to overheating.