I've had Chuck service my units for years.
They were cheap builder grade units and he made them perform better than they had in years. When it came time to replace them, I had three reputable companies give me quotes. I brought Chuck in last and without knowing what the others bid, he came in well under their bids. That made it so easy.
He put in some great units and had the keys to my house for a few days while they were in and out. I don't know of any other contractor I would trust absolutely with my home with no one home. Choosing Chuck was a no brainer.