Since this is the LED Flashlights forum, I'll assume you're asking about flashlights that use 5mm LEDs (vs just asking about 'loose' LEDs).
The current (3rd-gen) Inova X5 uses Nichia CS 5mm LEDs. I don't know whether it's "the brightest" (I've heard it's about 25-30 lumens), but it is very reliable/durable.