Sinningias are the best gesneriads. Everybody agrees on that, so get over it. They have pretty good flowers and most of them are easy to grow, tolerating neglect, temperatures around freezing, and abuse on the light stand. Plus, they have tubers, which means that they live a long time.
Species in Sinningia and the closely related genera Vanhouttea and Paliavana (all sinningias, really) belong to a well-defined taxonomic group of about 85 species. As you will read below, Sinningias are not only beautiful horticultural subjects, but are among the most diverse groups within the New World Gesneriaceae. Plants can range in size from the tiny Sinningia minima (aptly named) to large shrubs nearly 2 m in height such as Paliavana prasinata. Flower colors range from white through shades of purple to red and even yellow. And while many species grow on slopes in or on rocks, species such as S. allagophylla, S. elatior, S. sellovii, and S. tubiflora are terrestrial, and there are even a few that can be found growing on other plants as epiphytes.
You can read through this article for all kinds of information about this great group of Gesneriads, or you can proceed straight to the Genus Pages for Sinningia, Paliavana or Vanhuottea, where you will find a great many wonderful pictures and much additional detail.