When Ovi was at his peak, it was the Caps. But the Sid vs. Ovi debate is long over and so the rivalry has died down.
Now it's the Flyers again. Their fans have always been a bunch of degenerate chest-thumping mongoloids who are somewhat bummed that they're at a Flyers game and not a pro-wrestling event, so they've easily maintained a close 2nd to the Caps the whole time. It's crazy. I mean, you serve Red Bull to several thousand orangutans and affix them in orange t-shirts and seat them in Wells Fargo Center, you'll get almost the exact same narrative, career prospects, and cumulative intelligence... And physical attractiveness. But now that they've collected such an outstanding mixture of ogres and ovaries, they're just so much more easier to hate.
I have very little hatred for the Rangers however.