Tatuaje does a great job of keeping it simple, elegant, and recognizable. Their monster mash box was next level.
I would also agree BLTC has some great designs, but if you want unique and some items that stand out - Viaje is a trailblazer in that aspect. Their concepts are unlike anything else in the industry.
And last one for me is ADVentura. Every box is so unique and fits perfectly into the overall brand. I'm a little partial to the Explorer Torpedo, but definitely check out their stuff as well!