It's funny that I am going on a different direction than you, went from 60% to TKL because the lack of F-row and arrows in 60%. I tried poker layout, Tsangan and HHKB. Tsangan is probably my favorite one, because I can do mod-tap from qmk/via to turn my left alt, winkey, ctrl and shift into arrows. If you are looking at customs, bakeneko60 is open source and you can even modify the case yourself to your liking. HHKb definitely is more unique to me because it is topre, which give a pretty nice typing feeling and sound.