Both of these teams seem to like a little gold with their black but it's the Senators who add in the red to make the logo stand out a bit more. The Penguins logo just feels so flat. And there's the penguin wearing the hockey gear.
Since Senators make the laws, it seems to me that they have the upper hand on the Penguins as they could choose to protect them or not.
The better features of these two logos have recently been pointed out to me by readers. The golden triangle has significance to Pittsburgh. Also the gold circle in the Senators logo makes an "O" for Ottawa while you could say the red galea creates a "C" to symbolize Canada. If that's the case, it means the Maple Leafs and Oilers are the only Canadian teams not to work in a "C" of some sort. But I digress. The point is, the Penguins logo comes off like a '60s cartoon to me (go ahead, take your shots now). I'll go with the centurion.