Cooper installed my furnace/AC system 2 years ago. Their sales people were knowledgeable and worked with me to figure out the best system for my needs at a very good price. The install went flawlessly, the system is working great and the service people are polite, capable and up-to-date with technology.
However, the yearly maintenance plan costs about 20% more than other companies in my area. That may be because it includes an extended warranty plan, but I'm not sure it's worth the cost since my system will almost certainly outlast even the extended warranty. Also, it can be hard to get an appointment in Colorado Springs. I called in late September and the earliest available was Dec 11. Next year, I'll call in July.