Re: Are these the brightest rear/brake/turn LED's
You can spend years and hundreds of dollars trying all sorts of different LED bulbs that are available. I have not tried anything in my 2012 Overland, but thats basically because I have tried all sorts of LED setups in previous vehicles of mine. Basically, there are NO aftermarket plug and play LED bulbs that come anywhere near as bright as the original incandescent bulbs. Sure, they may have decent brightness at night, but in any other conditions they come far short.
I know your original question was which LED bulb is the brightest. Well in my experience with LED's, the higher number of LED's did infact make the bulb a little brighter if that helps answer your question. But make sure they are the SMD LED's.
The only other problem I see if that the Grand Cherokee tail lamps are large and not as centralized, so this makes me think that the LED will have a hard time focusing its light. Aftermarket LED's tend to become VERY dim in any sort of day light situation.
I am not even going to mess with trying to install a LED tower bulb in my Grand Cherokee. I will be waiting to either purchase a 2014 Overland, or if I dont want to get a new Jeep, I will see if the new 2014 LED lamps will somehow be plug and play on the earlier models. Anything else is just not worth it.