Wellesley’s econ is known for being particularly strong. Is USC (socal not carolina) really that bad? What about research opportunities, internships, and (most importantly to me) grad school and career placement?
Wellesley would provide a better experience in almost every aspect by far. Being a liberal arts college, its professors are devoted to teaching rather than research, and the small class sizes would allow you to forge close connections to your professors. There are probably not many (if any) classes taught by TAs. The students are collaborative and empowering, and intelligent and curious and devoted. Wellesley has a great reputation everywhere, in academic circles especially, so grad school should not be a problem.
Another vote for Wellesley, but you should also be aware that USC has better weather, and is probably less competitive. Econ at Wellesley is the most popular major and is extremely intense. W has a notably strong alumnae network and is well regarded by every grad school in the country. I imagine USC is also strong with regard to grad school placements, but I don’t know anything about their network.
The Thematic Option at USC may possibly offer the liberal arts college-type experience, but that is only for the first 2 years.