This is a loaded question… not that there isn’t a best, but the reality is there are several in the same realm that might be considered THE BEST but depending on your preference. Don’t get me wrong, there are some that are AWFUL!! But to point out 1 “best” is tough.
The JW Speaker 8800 Evolution has long since been revered as the best LED 4×6″ sealed beam headlight housing replacement on the market. However in 2016 a few other options entered the scene and there is some pretty stiff competition! So first let’s talk about what makes the JW Speaker 8800 one of the best:
The JW Speaker 8800 4×6 headlight is a single beam LED housing replacement that gives you either low beam or high beam in each housing, not both. They used to have a lifetime warranty but starting in 2017 they now only carry a 5 year warranty. They are manufactured right here in the USA in Germantown, Wisconsin, and they have one of the best and brightest beam patterns of any headlight in the world! Also February of 2017 there is a new 8800 Evolution 2 that comes in a heated 4×6″ version that is even brighter than the old one.
The Vision X Vortex XIL-46D is a new option for 2016 and the notable things about this headlight are that it comes in a dual beam configuration with both high and low beam in one housing! The Vision X Vortex and the JW Speaker 8800 are about the same brightness, but the beam patterns are totally different!
The fact that the Vision X Vortex headlight is dual beam is a HUGE deal. There is only one other on the market (United Pacific 31365) that is dual beam and the Vision X Vortex headlight is SO MUCH BETTER. If you need a dual beam 4×6 LED housing, the Vision X Vortex is really the best choice by far. Also it has an integrated LED halo / accent light that a lot of people like. You won’t get a halo type accent light like this on any other current model 4×6″ Sealed Beam LED headlight housing.
The Truck-Lite 4×6″ LED headlight comes in a single beam configuration only also: The low beam is part number 27640c and the high beam is part number 27645c. This headlight is cool because it has a kind of black-out look to it:
Truck-Lite was the first company in the world to make an LED headlight housing replacement for a sealed beam headlight, and they did that with the Phase 6 7″ round unit that was primarily used in the military on Hummers. Today they make a low-cost version for the 4×6″ that is light weight, and far less expensive than the other top-tier options listed here. The trade off of course is that the Vision X 4×6 and the JW Speaker 4×6 are vastly superior in terms of light output and beam pattern, but for the money the Truck-Lite option is solid.