I think people forget that Sakic was also injured a good number of games in his prime (Dead puck era, between the lockouts). Also some of hie his playoff performances were hindered during that time too.
People always remember Forsberg as the guy plagued with injuries but Sakic had his fair share too.
All said if both are impervious to injury it's pretty close. Forsberg was more physical and dynamic, stronger puck possession game, etc. Sakic was easily the better goal scorer, could be argued to have the higher purely offensive peak (95-96 and 00-01), leadership "intangibles", etc.
Their defensive games were sort of different. Sakic played positional defense quite well by the second half of his career. Forsberg was more physical and all, but mind you neither of them were ever considered shut-down selke-level defensive forwards, even though both garnered second place finishes in selke voting once.
And I hope people don't extrapolate that Forsberg is the better offensive player because he had a slightly higher points per game (although I understand voting for him for comparable offense + everything else he puts to the table). He only had a higher points per game because he didn't really play past the age of 33, and even using points per game is in his favour because he rarely played full seasons. You could speculate that maybe he would've been able to score at that rate or even higher barring injuries, but it's just that, speculation. Which is really what I don't like about the wording of this poll, because the answer depends so much on how you think a healthy Forsberg would fare. Would he have played better without injuries? Are his stats boosted by the fact that he got a lot of rest and rarely played full seasons? Would he have been able to continue scoring at that rate up into his older years? So many questions...
Just in case anyone is wondering, Forsberg from age 22-32 and Sakic from 20-31 both had a points per game of 1.29. The main difference being that in this time frame Sakic played 864 games to Forsberg's 593. Again, whether or not Forsberg can play at this pace for a prolonged time comes into question, and it's really a question that plays a major role in who you pick in this poll. So I can't really blame people for picking Forsberg, I'm just more of a skeptic and I don't like giving guys credit for what they didn't do while they were injured (even though it might go against the nature of the poll).
Personally, I am of the belief that Forsberg's style of play is an important factor in what led to his proneness to injuries. If that's the case, you simply can not have a healthy Forsberg with what everyone expects of him. In other words, if he were to remain healthy, he wouldn't have been as good as we remember him today. Flame away.