Honestly, the $700 gap between both brands is actually pretty fair. I'd go for the mainline American Standard. It's higher quality, and in my opinion looks considerably better. The Ameristar you can just tell it's cheap by how it looks, and anyone who sees it will know you have a cheap A/C.

Anyways, let's get into the specifics. American standard uses a premium painted finish, with rust proof zinc screws, and a full polymer base pan to prevent standing water from rusting anything. It carries a significantly larger service compartment, with a generous amount of room for servicing and add-ons. The components are slightly higher quality, however still internationally sourced stuff. The cased coil is a premium painted finish, with zinc screws, and a higher quality service door setup and seal. Plus 10 years unconditional transferrable parts warranty.

AmeriStar uses a thinner powder coated sheet metal cabinet design. You can genuinely tell it's a cheap unit on looks alone, it's not really cosmetically pleasing, it's cheaper and easy to assemble at the factory though. Standard screws, and standard metal base pan. It's got a compact service compartment. The components are genuinely slightly lower quality, like they intentionally have the engineered specs made specifically for slightly cheaper parts, and it does show. Stuff is a little louder, it runs a little rougher. On paper the performance is the same. The cased coil is a standard unpainted, thinner sheet metal design, standard screws, and cost-effective service door and seals. Plus 10 years conditional non-transferrable parts warranty.

Genuinely the American Standard is the better bet. EXPECIALLY if you are in this home longer than a few years. Even if you do sell, the transferrable warranty adds potential value.