Ok, let's just look at the last 2 seasons, but lets also consider usage, system and linemates as well. Over the past 2 seasons (Nylander's best):
Nylander 5v5: 1.07 G/60, 2.37 P/60
Aho 5v5: 1.11 G/60, 2.25 P/60
So Nylander has scored goals at a lower rate 5v5 and had assists at a higher rate 5v5. Overall points/60 are very close with a slight edge to Nylander. Now let's add the context and usage.
Nylander's Most common 5v5 line mates:
- Tavares 76 5v5 points (1056 min w/ Nylander),
- Matthews 118 5v5 points (756 min w/Nylander)
- Kerfoot 67 5v5 points (716 min w/Nylander)
- Bunting 94 5v5 points (714 min w/Nylander
Aho's most common 5v5 linemates
- Jarvis 57 5v5 points (1120 min w/ Aho)
- Teravainen 43 5v5 points (1007 min w/Aho)
- Svechnikov 71 5v5 points (610 min w/Aho)
- Necas 67 5v5 points (508 min w/Aho)
Clearly Nylander is playing with higher scoring forwards than Aho has played with. There's no denying that and it matters, but even so, he has scored at a lower rate (G/60) than Aho 5v5.
Now, on to the PP where Nylander had a higher scoring rate than Aho over these two seasons:
Nylander: 6.58 Points/60 (59 points)
Aho: 5.44 Points/60 (43 points)
But again, we must add context:
1) over these two seasons, Toronto had the 2nd rank PP in the NHL and Carolina had 18th ranked. Clearly Nylander is on a much better PP unit. Now, admittedly, some of that could be due to Nylander himself, but Matthews, Marner and Rielly are excellent PP personnel.
2) Nylander's most common teammates on the PP were: Tavares, Marner, Matthews and Rielly (by a large margin). Aho's most common line mates were Svechnikov, Teravainen, Trocheck/Necas, DeAngelo/Burns.
Clearly Nylander is playing on a much more potent PP with much better talent. Again, I don't think that's debatable.
Lastly, as a center and on a Rod Brind'Amour coached team, Aho can't hover at the blue line and fly the zone early like Nylander can and does. I watched the Leafs a lot and I see it often. I'm not complaining about it as I'd do the same thing as a coach, but I'm pointing out a difference in how they teams play and how it leads to scoring chances.
Based on all this, I don't conclude that Nylander has been better offensively than Aho. I do think Nylander very well could be better though. He's a very skilled guy and I'm a big fan of his, but until he's used in the same situation as Aho, with the same teammates and the same responsibilities, their numbers are close enough that it's not conclusive to me, when accounting for the differences in teammates, system and usage.