The NHL has been around 100+ years and there's only three players in history with 800+ goals -- Ovechkin, Gretzky, and Gordie. You don't flub your way to 800 goals by being "just another star player." Sure, Ovechkin is not a 200 foot titan... and we can pick holes in his game all day if we choose to... but when you're the only player in hockey history who has a chance to surpass Gretzky in goals, you probably need to be considered generational imho. Hell, the closest active player to Ovie in career goals is Sid and he's 250+ behind him in 21st place all-time. So, in terms of goal scoring, Ovechkin has left his generation in the dust. The scary thing is, I still have him on the fence of generational. But if I'm grading on a curve and loosening admission, Ovie probably gets the nod over guys like Bourque, Lidstrom, Crosby, Yzerman, etc. For me at least.
Not looking to derail from Bourque, but how would we consider Housley if he scored 2,000 points as a defenseman, even with his defensive shortcomings and softish play? Although flawed, wouldn't we likely consider him generational if his offense was that astounding?
But as someone else said... I guess we need to agree on the definition of "generational."