I can't believe this thread is still going strong, so I'll contribute.
There's a difference between being the best player during his time at Iowa State and being Iowa State's best NBA player.
Tyrese is well on his way to being Iowa State's best NBA player (I think he's there already). There's no universe where Jamaal was the better pro than Tyrese.
As far as being Iowa State's best player, there's a world where Tyrese would have worked his way into that conversation. If he doesn't get hurt and if he stays for 4 years, I'm guessing he'd be right there. But we had him for 1.5 years when he was still growing and learning as a player. Jamaal was 21 and had already grown a lot before he even got to us. My guess is 18 year old Jamaal would have been a bit rough around the edges. So you can't compare the two of them at Iowa State, they were totally different things. Jamaal had the better Iowa State career, but it would be interesting to see how their junior and senior seasons would have compared.
Another thing is we all judge best Iowa State player differently. Some only care about the record of the teams. Some put emphasis on how long a player was around. Some want to say whoever had the best pro career.