I used to use a 2x'AA' maglite types after trying numerous others. Now I use a couple of those newer LED types. I have a blue/white LED torch to use for normal lighting & a red LED one for cockpit stuff.
Each has a momentary 'on' as well as a lockable 'on'. Brigtness levels are fine. I can - just - see the wing tips at night, including any ice.
There's quite a few designs being released now, including some with multiple LEDs & larger batteries for brightness. Mine are an appropriate size for a key ring & use 2 x watch batteries and a single LED for a bulb.. I find mine to be ideal.