“La’Omer” or “B’Omer” — Which is Correct?

When counting the 49 days of “Sefirat HaOmer”, some people say “La'Omer” and some say “B'Omer”. Which is right? Doesn't the fact that EVERYBODY says "Lag B'Omer" prove that "B'Omer" is correct and not "La'Omer?"

A great Rabbi from the previous generation, Rabbi Nachman Bulman, explained to me that “everyone” refers to the 33rd day as "Lag B'Omer" because the main proponents of saying "B'Omer" are Rabbi Yitzchak Luria — the Arizal — and the Sephardi Kabbalists. Celebrating Lag B'Omer with bonfires, music and dancing is largely rooted in their Kabbalistic teachings and traditions.

Regarding counting each day, in general, most Rabbinical authorities write that "La'Omer" is correct. However, both ways are valid, and there is no reason to change one's custom. In fact, even if you say "Today is day such-and-such" — omitting any reference to the "Omer" — you still fulfill the mitzvah.

By the way, not everyone refers to the 33rd day as "Lag B'Omer"! The Shulchan Aruch actually refers to it as "Lag La'Omer"!

Which reminds me of the two Jews who argued during their entire plane ride regarding the correct pronunciation of Hawaii.

Upon landing in Honolulu, they asked the first native on the island "Is it pronounced Hawaii or Havaii?"
"Havaii," he replied.
"Thank you," they said.
"You're velcome," said the native.