OK, my turn. I live in suburbia, but solo hike and backpack in woodland areas that are typically a minimum of one days hike back to civilization and often more, which means that if I get into trouble, it's either self-rescue or no rescue. (More on this in a bit.)
In town I typically carry three lights, with backup lights and spare cells in the car (I consider forehandedness a cardinal virtue.) In winter I like my FourSevens Quark 2x123, with a 16650 cell; an EagTac D25C Ti (modded by SkyLumen with a high CRI emitter and a boost driver...800 lumens on Turbo); and one of several AA/14500 lights, in case of utter chaos, in which case AA cells may be the most easily scavenged.
In warm months I opt for lightweight lighting tools, most often a FourSevens Mini 123, and a AA/14500. (Backups still in the car.)
Backpacking is another matter. As I wrote, I hike alone. Two headlamps (18650), two flashlights (18650), one Luci inflatable 4000 mAh lantern, and one AA/14500, and one AAA, both of these as insurance against the remote chance that my other lights might fail and I need to beg another hiker for a spare cell. (I've only encountered two other hikers on trail who use 18650 cells in their lights...most are content with AA/AAA powered lights, or internal rechargable cells.)
Recently my wife has become more anxious about my solo adventures... she's not amused by tales of narrow misses or disasters averted, and now insists that a buy a satellite communication enabled rescue beacon before going off grid (established campgrounds are OK with her, but hikes in the Sierra Nevada, not do much.) Even though I may now may be able to summon help via satellite, I still need to survive until help arrives, in which case the multiple redundant lights are still "essential kit."