This will go to the Penguins, mostly due to marquee value. Let's be brutally honest.
The Hawks teams, to a man, were better "teams" with better "overall talent" for sure. They've won Cups, then had to get rid of players like Ladd, Byfuglien, etc. and they still won more Cups. They were rock solid in goal, had an elite, top D-pairing, one of the elite wingers (Kane) and a leader up the middle who could rival Sid in that department (Toews). The Pens won Cups thanks to Sid, Geno and a Fleury/Murray tandem. Letang couldn't hold Keith's stick, and the Pens won without him anyway. Kessel, while very good, is no Patty Kane.
The Hawks were deep and loaded, the Pens were top-heavy, but very fortunate to get outstanding production from players who stepped their games up in the playoffs like Kunitz and Guentzel.
So, the Hawks, were "better teams" IMO but the Pens had 87 and 71 - the two best players out of either team. And Sid will likely go down as a Top-10 player in NHL history when it's all said and done.
The Pens win this on style points.