Right now, definitely Eriksson. Not saying that Nilsson is a poor prospect by any means, only that Eriksson has clearly surpassed Nilsson this season.
Eriksson (or "King Loui" if you prefer) has been praised a lot by his coach Conny Evensson and even more by team Sweden's U20 team coach Torgny Bendelin. In their opinion it seems Eriksson is even a better prospect than Steen.. which is something I am not yet totally convinced about.
As for Nilsson .. the big question is where will he play next season? His old SEL team Leksand will likely get relegated from the SEL.. and I don't think he wants to go back there anyway. He wants to play for Djurgården but their economy is not directly excellent and obviously there is a risk signing a player like Nilsson .. who has been struggling big-time this season.
I predict a SEL team will pick him up though.. but I wouldn't be surprised if we'll find him playing in North America next season.