Oh Loki is going to win. Ren couldn't even defeat Rey how will he defeat Loki. He'll play his hologram trick. Kylo Ren will be in a real fix in trying to find out which one is the real Loki. This way Loki will defeat Kylo ren. And his force stuff won't stand in front of loki.
Loki would for sure win. Yeah Kylo Ren has the force and a saber but Loki can play hologram and Ren kills Loki's hologram just to find out the real one was hiding and now he's in trouble. Then again, Kylo Ren should use the force to know that sort of stuff. So Loki would win since Kylo Ren is not to bright plus he lost to Rey when she wasn't fully trained.