I like KLK more, it's just more entertaining.
GL...it's great, there is no denying that. The art, the OST, the feels, all great.
But on a by-episode basis KLK just has soooo much more.(That and the second season of GL kind of dragged on during the space phase, the first half was great but the second half had a 2-3 episode dead-zone).
That and KLK i feel has more "characters" by now. GL had a lot of characters that were meant to be supporting but by the end I just switched out their faces with one another.