all-time if you take away Lebron and his teams (the Eastern Conference has been pretty bad other than Lebron since 1999, with a few exceptions sprinkled in).
It is kind of funny that now that Lebron has moved a ton of talent is going out and developing in the East. Kawhi, Butler, Harris, Gasol, Mirotic, and more. Add that to guys that are growing into their own stardom in Antetokounmpo, Embiid, Simmons, Tatum, Oladipo, Kemba, Sabonis...etc. The top of the East is as strong as it has been in quite some time.
That being said, would it surprise you to know that there are only 4 teams in the East with winning records against the West? Only 4 out of the 15 teams in the West have a .500 or worse record against the East (Lakers, Pelicans, Grizzlies and Suns).