http://forward.com/fast-forward/371700/looking-for-a-holocaust-historian-google-suggests-leading-holocaust-denier/
According to the news article, cited above, the answer that you get from google is first David Irving and then Deborah Lipstadt.
The following quote is from the news article:
Begin quote
David Irving is certainly a Holocaust historian, I guess. But mostly, he’s “antisemitic and racist,” as an English judge once called him, and a leading denier of the Holocaust. He was even jailed in Austria for more than year for Holocaust denial, which is a crime there.
The search turns up plenty of Holocaust historians with sterling records, as well — Deborah Lipstadt, the former Forward columnist who Irving once sued for calling him a Holocaust denier, is the second result. I think I’ll call her instead.
End quote
David Irving is a walking encyclopedia and he knows history backwards and forwards, but he is not a Holocaust expert. Deborah Lipstadt is a hateful Jew who knows nothing about anything.
If you want to find the best Holocaust expert, I would suggest that you google “best Holocaust denier” to find the answer to this question. The term THE Holocaust is not a true account of history.