DS9's Ferengi episodes are a mixed bag. While there are some great ones (Little Green Men) there are also some dire ones (Profit and Lace). Overall, though I enjoy most of them, even if sometimes they were perhaps a bit silly.
But DS9's strength was in inserting humour into regular episodes. Garak always provides a laugh, but there's also this gem between Quark and Odo from The Way of the Warrior:
Quark: If we get boarded I'm going to defend my bar with this.
Odo: A box?
Quark: No, what's inside the box.
Opens box to reveal a piece of paper which Odo picks up.
Odo: Dear Quark, I had to use parts from your phaser to fix the replicators. Hope to replace them soon, your brother, Rom.
Quark: What? The idiot! I'll kill him!
Odo: With what?
But yeah, TNG wasn't bad at humour either. Outside of the Q episodes, Worf had quite a few one-liners, and Dorn's delivery often made them sound five times funnier than they really were.