Among forwards, he is in the Hull/Beliveau tier; the two most popular picks for #5 player all-time.
Hull is there because he is, IMO, a Top 3 goalscorer, arguably #1, of all-time and an Art Ross contender for most of his prime. His playoff resume is lacking in Cups but he was a great playoff performer. He may have left another elite season or two on the table after jumping to the WHA at age 33/34.
Beliveau is the quintessential #1 C with elite goalscoring and playmaking, has one of the best playoff resumes in NHL history, and was still elite into his later 30's. Injuries kept him from winning more than one Art Ross.
Crosby is lacking nothing on his resume vs. these two to argue he doesn't deserve to be in their company. He also is the quintessential #1 C, it can be argued was the best offensive producer out of the three, and has the best playoff resume of his era. He is starting to create separation from them in longevity of prime with higher end point finishes and Hart nominations which, IMO, are enhanced by the fact that he is beating out more competition for these accolades. I.e. it is statistically more impressive to finish Top 3, 5, 10 in scoring, PPG, Hart voting etc.. in a 30 team league vs. a six team league.