If you want a 6 volt incandescent and don't want to pay for an A2, there's also the Streamlight TL2, basically similar to 6P but smaller, and it has a spare bulb tucked in the head assembly. The 6P is a classic though.

The Nuwai Q3 is sort of a poor man's E1/KL1, no momentary switch, and about half as bright as an E2 or 6P or L4. But it's an excellent value.