There are 2 kinds of twisties: "Crush your battery type" (CYB) which simply push solid metal contacts in on the battery; and the spring loaded type which constantly touch the battery ends and close the circuit when the end of the body touches a contact ring at the head (PCB) or tail. The CYB type is not as good because it conducts current through the threads, which can become gunked up over time and cause poor contact and flickering. The spring loaded type makes contact at the end of the body which is sealed inside and can be kept clean, so no flickering. Less important is no battery rattle with spring loaded type twisty, also.
Spring loaded type twisty lights include the Fenix L0x, E0, E1, E01, Fenix P1D, Fenix Civictor, Gerber Infinity Ultra, and the Rayovac 2AA Extreme Lux (tail twisty). The CYB type include the Jetbeam CLE, the old Fenix P1 model, Arc AAA, the old Arc LS, and the older Peak models (and I think also the current Peaks but I'm not sure).
I of course am partial to the spring loaded type twisty lights...