WM,
I live in Myrtle Beach, SC.
We sell mostly heat pumps here. I used to sell a lot of Goodman equipment when I first started. However, they do not last as well as some other brands, like Lennox and Trane and York. Typically a Lennox will outlast a Goodman by 5-years. In addition, they are very loud. I can hear my neighbor's Goodman OD unit when I am sitting next to my Lennox while it is running. I consider quiet operation to be part of comfort. I stopped selling very many Goodman units because of warranty and out of warranty problems.
Yes, they are easy to install. If you are only going to live in your house for a couple of years, then move; the Goodman can be a good deal if the sound levels don't bother you. The first cost of Goodman is lower than Lennox, but over the long run, the Lennox is cheaper.
Of course not all Lennox dealers are equal. We have one Lennox dealer in my area who is charging double my prices and doing a hack job.
My feeling is that when you buy from a Goodman dealer, you get a Goodman job.
Just because it is a 14 SEER unit, does not mean you will get 14 SEER. The equipment must be sized right; the ducts must not leak, The air flow must be correct, the charge must be correct. Otherwise a 14 SEER unit can deliver 9 SEER. Most Goodman dealers do not do REAL load calculations, they size by the square foot of floor space, which is WRONG. They do not flow nitrogen when brazing the Freon lines, which is WRONG. They seal the ducts with unapproved tape instead of approved UL181 A-P tape or mastic. They do not measure air flow with a hood. They do not have good tools to check refrigerant charge. They do not size lines properly.
You can do a proper installation with Goodman, but if all you have to offer the customer is a low price, you cannot afford a Flow Hood ($2,000.00 & up), Blower Door ($2,700.00), Duct Blaster ($1,800.00), Sling Psychrometer ($100.00 per truck), Load Calculation and Duct Design software ($600.00 to $2,000.00); Nitrogen Regulator and Flow Meter ($300.00); etc. Low price is not always best price. That goes for the equipment as well as the contractor.
End of rant
Stretch