I came across this thread since I'm looking to upgrade from halogen on my 2016 GC and I saw that no one posted anything helpful so I decided to some research for the greater good of the community.
First and foremost,
the type of headlight on your truck is of utmost importance which is in line with @raminan's comment.
Apparently, LED's work very well in reflector assemblies but not so well in projectors. HID's on the other hand, work well in both reflectors and projectors. Interestingly, some headlights can be hybrids - projector for the low beam and reflector for the high beam - in which case you can mix and match LED's and HID's based on the type. (
source)
From my findings, up until the 4th generation (1993 - 2010), all GC's had reflectors for both low and high beams, although it may be possible that some higher-end 3rd gen models had some projectors (not 100% sure on this one). 4th gen models are definitely equipped with projectors for at least one beam so you definitely want to avoid LED's for any beam sporting projector lenses (this applies to you
@glhamden for your 2020 model).
Recommended Buying Options
As for bulb suggestions, my research was focused on studying several review sites. Almost all of them ranked Cougar, Hikari and XenonPro as the best bulbs for LED while an overwhelming majority ranked XenonPro as number one for HID's.
Although Cougar and Hikari are more competitively priced, their 1-year warranty kind of turned me off compared to XenonPro's lifetime warranty. I personally rather pay a premium for piece of mind.
I should be receiving my lights early next week and will follow up with pictures, results and experience.