What are the best and worst air conditioner brands?

Best and worst air conditioner brands are typically ranked by reliability, efficiency, quietness, warranty, and parts availability based on contractor surveys and consumer reports. Best tier brands consistently include Trane and American Standard which are known for exceptional durability and low failure rates, Carrier and Bryant for high efficiency up to 26 SEER2 and advanced variable speed technology, Daikin for inverter and VRV technology and world's largest HVAC manufacturing scale, Mitsubishi Electric for ductless mini-splits and cold climate heat pumps, and Lennox for ultra-high efficiency up to 26 SEER2 and very quiet operation. Mid-tier good value brands include York, Rheem, Ruud, Heil, Tempstar, Keeprite, and Arcoaire which offer 90 percent of premium performance at lower cost and use universal parts that are cheaper to repair. Worst or lower-rated brands are typically ultra-budget builder grade brands or older designs that have higher failure rates and expensive proprietary parts, with consumer complaints often citing Goodman entry-level models for higher service call rates, though Goodman has improved since Daikin ownership, and some low-cost imported brands with poor parts support. However brand alone matters less than installation quality, as even the best brand will fail early if improperly sized or installed without proper vacuum and charge.