Ed O'Neill was typecast for quite a while after the show ended, he was lucky when he got the role on Modern Family and Finding Dory. Katy Sagal has had the most success, she's had numerous roles on popular shows, she still looks great at 63.
Katey has had the most consistent success of the group. Between Sons of Anarchy, Futurama, and few 1 season shows, something called Superior Donuts that she's doing now, and guest spots on many shows (including Lost and Big Bang Theory) she's pretty much always had something going on.
Ed O'Neil was relegated to mostly guest spots and voice work until he hit big with Modern Family. He had a few 1 season shows, including a Dragnet remake that I forgot about.
Christina Applegate had the most success in films, and a few shows to boot, but is kind in a slump now.
EDIT: I forgot that on top of all her success, Katey had a really bad break in her post MWC career. She was on "8 Simple Rules for Dating my Teenage Daughter" with John Ritter when he suddenly died at the start of the 3rd season. They found a way to finish that season, but they had to end it there, when it could have run 2 or more seasons.
And David Faustino was in Sharknado 4................ I'll leave that right there.
& Katey had a nice role in a tv movie a while back, I believe for Hallmark where her character is dying of cancer and she arranges to find her husband a fine woman to marry before she passes away. It's really quite well done and of course very sad, but, ultimately uplifting. Sagal does a terrific job there.
Probably a tie between Ed and Katy, Katy having the more prestigious roles of the two).
Christina was the one we probably all thought would go onto be huge but never really made it that big.