I had Reliance install a new AC unit in May of this year to take advantage of spring promotion they had going. They were by far the most competitive with their pricing! When the guys came to do the install they were efficient and very professional, they were happy to answer any questions I had, and explain the installation process. When they were done they cleaned the work area, it was cleaner when they left than it was before they started.
There were some wiring issues with my thermostat, but when I called Reliance they sent a tech the very next day and he installed a brand-new Nest thermostat, got everything running well and even sealed up some leaks on the furnace manifold to make it more efficient.
Some notes, Reliance has (in the past) been aggressive in promoting AC rentals rather than sales, never rent that is a total waste of money and the terms (based on past research) are generally unfavorable. They did sign me up for some monthly maintenance plan by default which I objected too, but it was addressed in a quick two minute phone call.
Overall, Reliance had great pricing, great customer service, and took great care when I had issues. They were genuinely great to do business with and I'm very happy with my AC purchase.
I'll update this review to include notes regarding long-term ownership and service quality/pricing when the time comes.