Nikolaj Ehlers is a great young, proven skilled player who can play in the North American style of hockey. Ehlers aside from having proven independent skill, he's a great team player and a winger to boot and a left winger at that. He thrived on the Halifax Mooseheads playing with talent like Nathan MacKinnon and Jonathan Drouin. He could easily fit in on a third or even second line with his playing style on the Leafs AND be playing for them in the 14-15 season.
William Nylander is a centerman who did not play a full season of hockey last year. Leafs needed a left winger, or if they had picked up a d-man that could have been excused too depending on the selection. Nylander has a lot to prove to beat out prospect Frederik Gauthier for a centerman spot if one becomes available.
That being said, with Toronto's track record of draft picks and conditioning time periods with said picks, it's not overly surprising the way they made this pick. Disappointing Brendan Shanahan let this happen being the new commander of this franchise. Nylander will not see any NHL time in the upcoming season, this is a wasted pick by the Leafs without a doubt.