I think today's common size general purpose flashlight is the two AA size. Many options. E.g. Fenix L2T is a common recommendation, but Fenix has other models and most other manufacturers also have a selection.
Think about what your priorities are. How bright? How much runtime? (Which is more important to you? They tend to be traded off.) Modes? A low or med-low is ideal for many (most?) things, especially indoors. But "what's that over there?" situations often demand bright with good throw. Some lights offer other modes too. I'm not sure I'd ever use flashing modes, but some people like them and some user interfaces keep them out of the way of everyday use.
Of course, this site will expose you to many other options. (Bigger, brighter, smaller, longer running, and certainly more exotic.