KT lcd 1 right thru to KT lcd 12, there are some 15 or 16 different displays.That's ok. Which display do you use and why?
It all depends what you want .
Basic no thrills displays are lcd1 & lcd2 , I recently re- tro fitted a KT set up to a step thru bike for someone replacing the crappy speed control stuff. I set the bike up and opted for a KT lcd 1 for them so they can't mess up the settings which I know they did before, I didn't want them to fiddle them come back to me to sort them out.
Some of the displays have integrated thumb throttles and one can choose L or R thumb throtttle, some are colour or B&W. Some large some small.
LCD4 is a bit fiddly , tiny and discreet no use with winter gloves, LCD 5 is fairly popular but personally I'm happy with the prominent LCD3.
Takes your pick and choose they shoud all work ok and all will be compatible.
Just check the suppliers if buying from different sellers as some use KT custom stuff and one may find connectors are opposite from stock KT connectors from the factory .