I think it's gonna take something incredible to ever knock LLL out of the top spot as my all-time fave.

EOINA was definitely a character-heavy episode...good for a season-finale. The "Be Still My Heart/All In The Family" coupling (where Lucy dies) also ranks up there as one of the classics for me, as does "Ambush (the live episode)" probably because of how incredible it was to watch it as it happened. For the whole Carol/Doug thing, wouldn't you just die without the reunion in "Such Sweet Sorrow" when she finds him at the dock and they go to each other? *sigh* Great ending for those two.
I'd have to throw the entire seventh season in as a favorite simply because of the whole angst-filled Kim Legaspi/Kerry Weaver thing. Saw that one coming a mile away in "Mars Attacks" long before I knew there were spoiler sites in the world. Here was this new character, interacting specifically with Kerry, tossing in subtle little compliments about clothes and glasses. Good writers don't write unnecessary lines, so I knew there had to be some purpose in their interaction. Found out later -- there was.
I still get excited waiting for ER on Thursdays and when those first little notes play and one of the stars says, "Previously, on ER...," I'm all there! But I can't deny it's running neck-and-neck now with "Third Watch." I first started watching it off and on before 9/11. One of the stars (my fave, Molly Price - "Faith Yokas") is married to an FDNY firefighter and after 9/11, the TW crew produced a special-episode called "In Their Own Words" where actual FDNY's, NYPD's, and family members talked about what happened that day. Then I watched the following two week's episodes called "September 10th" and "After Time," which showed how the fictional FDNY's and NYPD's of Third Watch dealt with 9/11. After that I was hooked. They carried over the aftermath of 9/11 into subsequent episodes, writing it into the characters' lives, with one officer coping with his stress and anger over the course of several weeks and with a firefighter dealing with the recovery of her father's remains at Ground Zero several months later. It was all very cathartic.
Since then, *sigh* it's been nothing but pure, unadulterated, wonderful, romantic angst between two cops - Bosco and Faith. Unrequited love at it best. Blonde hair, green eyes, babe with a gun. *falls over on the floor* It's heaven.
And, of course, ER and TW have some of the same writers and directors. So, you know I just gotta love it.