akali or katarina

I have previously been a kat main, but that didnt work out too well so when i got introduced to akali i was amazed by how easy and op her kit was. i have picked up alot from akali but im wondering if i should go back to maining kat since im alot better now and kat just seems to have a larger impact in teamfights and lategame in general. also, i was horrible at farming with akali(2.3cs/m). what champ would be better to invest in long term and why?