Bobby Hull at Crosby's age was a 9-time 1st team all star, 7-time Hart finalist (2 of them wins), 3-time Art Ross winner, 7-time leader in NHL goals, 3-time playoff goal leader.
He was also a clear 2nd in points over that time period and didn't separate himself from the pack in PPG at all, in fact there was basically a 4 way tie for 1st place in PPG.
Player Season Finder | Hockey-Reference.com
He was also 2nd in points in the playoffs and in a huge mix for PPG during that time period.
Player Season Finder | Hockey-Reference.com
Another point in separation between Crosby and Bobby Hull was that Hull didn't become elite until his 3rd full season and his level of play wasn't elite during his 4th and 6th seasons was very good but hardly elite.
The 1st team all star comparison is a bit misleading though as the competition for LWers during that time was quite a bit weaker than for centers during Crosby's era.
That being said Crosby has 8 seasons as a (4)1st or (4)2nd team all star center and 2 times finished in 3rd place.
Bobby Hull is one of the guys (Beliveau, Bourque and Lidstrom are the ther main contenders) that I have in the battle for 5th place all time (not going to include goalies here as it's difficult to place them with position players but Roy and Hasek are in the mix to be sure) and he is likely to have a better age 32 season than Crosby, due to crosby being injured.
Hull also had an excellent age 32 season and I for you do not discount his play in the WHA but it's hard not to say that Crosby has had a higher and more consistent level of elite play in the regular season and playoffs through the age of 31 and I think it will be the same after their age 32 seasons as well.
One telling point is they both have 11 top 10 scoring finishes in the NHL
Hull 1,1,1,2,2,2,4,5,6,7,9
Crosby 1,1,2,2,3,3,3,3,5,6,10
So taking out duplicates we are left with
Hull 1,1,2,4,7,9
Crosby 3,3,3,3,10
Given the size of their leagues and level of competition for top 10 in scoring, Hull was basically playing in a 6 team league the entire time as the new expansion teams didn't have any top 10 scorers in the years Hull was in the top 10 except several guys sprinkled in the 7-10 spots and usually only a single player.
I would take Crosby as being ahead due to his consistency and point production in the regular season and playoffs over Hull up to age 31.