I specialize in high rise building security and have worked several sites for my company. I find that each site and each shift presents different flashlight needs, so my comments should be taken as generalizations. The following are lights that I keep on hand, with an explanation of why I have them:
MagLite 3C with Malkoff for throw or if I feel the need to have something in my hand.
SureFire 8AX for those shifts that require a lot of light usage, also useful for outdoor patrols.
SureFire 6P with Malkoff M60 is my belt light of choice for working second or third shifts. I'm glad that I have it and quite happy that it doesn't see much use, but when I need to use it, the need is urgent.
SureFire E1L (uniform) or Fenix P1 Cree (coat and tie) are my two most used lights and handle 90% of my lighting needs.
My keychain light is a Peak Matterhorn, which also sees regular use reading fire extinguishers, control panels and working on guard station computer problems.
Generally, I can get free AA and D cells from a high rise buildings engineering staff, but mostly forget to do so. I keep a MiniMag LED 2xAA and MagLite LED 2xD on hand as loaners or in case of a power outage, but they see very little use.
I frequently get called to work overtime shifts at other sites (armed and unarmed) and usually find that my work light collection ranges from adequate to overkill. Frankly, if the situation is such that I need even more specialized tools, I ain't taking the chance of working there again unless someone else is buying.