If we particular talk about the generic range of lens focal length, it would be 35mm, 50mm and 85mm. 35mm is best for indoor conditions. Similarly 50mm and 85mm is good for outdoor conditions. 50mm is somewhere between indoor and outdoor.

For generic purpose, 50/35mm are mostly used. Aperture f/1.8 lenses are cheaper and preferred. For high bokeh, f/1.4 lenses give good results but they are pretty costly.