You may say 'suki ja na katta'.
naisushotto
Japanese would say sashiburi
subarashii video
It's Japanese for "nice" if you say that to a object If it's a human i think it will be "nice looking"
'Anata ga yasashii/shinsetsu desu.'
Watashi WA chonaisu desu
kono kyokku ii ne
sanpatsu ga ii desu ne!
Ii keshigomu desu, ne?
いい男 (ii otoko)
I don't think they nice because articels say they can leave serious injuries caused by their claws.
there is really no expression for 'be nice' but if talking to children you could say ii ko ni shitte