The Who figures for the most part are very well sculpted, and have decent articulation (At least after the first wave). There's also a lot of variety in the Doctor's themselves, although there are some notable exceptions. While not perfect, they are way, way better than the late 80s Dapol line, which had figures that looked more like they were made in the 70s.
As for the expressions, the first Tom Baker figure had swappable heads-one with the hat and the classic grin, the other with a more serious expression similar to his title sequence. However most of the Tom repaints/rereleases have gone with the serious head. Likewise, some of the McCoy figures also have a smiling expression.