Title^
Biggie understood flow. However the direction of his short career was driven by Diddy who was trying to prove he could make it on his own and didn't need Andre Harrell. The only way to do that was through commercial success. I ultimately blame Diddy for Biggie's death. Diddy has control of the PR and song releases for Bad Boy. When they released "Who Shot Ya?" ... that was it.
2pac was a poet. You're not going to find the same level of popular music. 2pac was notoriously bad at picking beats. This is why when he linked up with Death Row and the talent that was being nurtured there is when he exploded. But 2pac, like big, found the wrong role model.
When you're comparing to the two, you run into the same issues you have when you're comparing Kobe vs. LeBron. The expression of basketball for each player is different. You're not going to stop LeBron if he wants to go to the rim. Just like you're not going to stop Kobe if he's going to the top of the key for the game winner.
Which ever you identify with is likely the person you think is better. If you're more interested in popular music and just want to have a good time, Notorious B.I.G is for you. You can get the same stuff from 2pac but if you want a deeper perspective and possibly the earliest conscious rapper, 2pac is for you.