The only commercially sold compressor brand manufactured in the U.S. is Arctic Compressor made in Superior, Wisconsin. They are mostly sold for commercial outlets like dive shops, fire departments, etc. They start at about $10,000 so individual buyers are almost non-existent.
Bauer compressors are designed and manufactured in Germany. Bauer is the most well-known air compressor company in the world. They are THE brand used by more fire departments, dive shops, and on luxury yachts to fill scuba tanks. They have more servicing dealers around the U.S. than any other brand. They are the gold standard of longevity and performance, but their price reflects it.
Alkin compressors are manufactured in Turkey and sold in the U.S. by a growing number of air gun dealers. Their service facility for the U.S. is in Clifton N.J. They are the fastest growing compressor dealer in the air gun market due to their affordability, construction quality, and excellent service reputation. Their price is not cheap but within reach for individual owners who expect reliability and service.
Coltri compressors are manufactured in Italy. They are considered a premium brand and have a good reputation in the scuba industry and in the air gun owner segment. Their chief asset is their portability, manageable size, and competitive price. They do not have many dealers in the U.S. and servicing has been an issue. Daystate rebranded several Coltri models but has discontinued several of them due to an inordinate number of breakdowns and customer complaints.
The air gun market has been flooded with a number of inexpensive high pressure compressor brands. The Shoebox was the first successful booster compressor. It was U.S. built and very well received until cheaper Chinese compressors forced them out of business. There are too many brands to compare here. Tuxing, Yong Heng, DAVV, Hatsan, Air Venturi, Umarex, etc. are just a few. They are typically hit or miss in quality control, metallurgy, and longevity. Some owners swear by them, and a large number swear at them.
Carette's newest air-cooled compressor looks to be a well-designed, serviceable compressor with lots of desirable features. If I were asked to name the best designed Chinese compressor, this would be the one I'd recommend. I'll leave the other questions posted in this thread about servicing and warranty experiences with the U.S. dealer for others to discuss and decide.