Welcome on board Kurt,
The highest quality of sculpting is broadly spread across a number of recent releases in a number of different series. You can't go wrong with pretty much anything released over the past 2 or 3 years, although some of the action-type poses in the WWII ranges necessitate corresponding facial expressions to convey the drama, and thus some of these are more successful than others.
However, to speak of a specific series I'd say that the Cross & Crescent, the Streets of Old Hong Kong or the Imperial China would probably offer the best combination of high quality sculpting and excellent standards of painting.
Always collect what you like. Napoleonics or WWII or the Alamo are not political parties, and you don't need to swear undying allegiance to any particular range.