It depends on your definition of best. Do you want the best build quality in a pistol slim on tactical features, or do you want the most features with acceptable materials?
New?
I really like the new Sig pistols, which are around that price range, for being loaded with features. They offer a lot of features for the price, but are not as "pure" as other models (external extractor, proprietary slide profile that can affect holster fitment). As to the model, they vary a bit. The C3 is very popular and is under $800 from what I see online.
Others like Springfield, which combines forged frames with nice feature sets for the price.
Still others like Rock Island, which gives you acceptable (by most measures) but by no means "superior" quality, well-regarded customer service, good features if you opt for the Tactical, and a hell of a price ($450 give or take depending on you location). TO some, the savings make them the "best."
I believe a Colt 70 series reproduction is just hair over $800, but would be my choice. In fact, it was. But hard and fast under $800, and/or I wanted more features than basic Series 70, I would get a Sig. Blasphemy I know