Yes, they are both big risers but Sennecke rose the most from mid-season to the end of the season. The argument is that if you see Sennecke as a 'riser' as a negative, then Iginla also qualifies as a riser, it's not a good argument to knock one down and simultaneously lift the other up.
It isn't about the extra 2 inches, it's about the fact that Sennecke was seen as a mid first round pick coming into the year as a 5'11" guy.. now those skills are in a near 6'3" frame and he showed a command and dominance with that frame late in the year and into the playoffs.
If you like the higher floor in Iginla, power to you, but personally, if i'm forced to choose one of Sennecke or Iginla, I'm going upside at 5, because I want a game breaking forward and Sennecke could be that where Iginla hasn't shown quite those qualities but you can be assured you are at least getting a Jake Debrusk level player and some people prefer that cost certainty.
I just don't think the debate of Sennecke vs. Iginla should have someone thinking an opposite opinion is wrong or lunacy.. the same way that I prefer Parekh to Buium, but the opposite opinion isn't lunacy there either.
People have preferences on what they like and value more and that's what we are really looking at here in this draft. This isn't like saying you'd rather take Iginla over Celebrini where there's a clear differential between the prospects at this point in time.