The campaigning has heated up ahead of Tuesday's balloting and Gantz's Blue and White party has inched ahead of Netanyahu's Likud in polls.
Here's a closer look at two men vying for the job:
BENJAMIN NETANYAHU: SEEKING TO MAKE HISTORY
If Netanyahu scores a fourth straight term and fifth overall, he will be on track to break the record as Israel's longest-serving leader. As a fixture of the Israeli political scene for over three decades, "Bibi" Netanyahu has become the face of Israel on the world stage.
Netanyahu sells himself as the only one who can protect Israel from the rising tide of Iranian aggression and accelerate Israel's global acceptance, nursing diplomatic relations with former adversaries across the Arab world.
But his rule looks more uncertain than ever after the attorney general's recommendation to indict him on charges of bribery, fraud and breach of trust. Allegations that he manipulated the press through shady deals and accepted lavish gifts from his billionaire friends have thrown his rule into jeopardy.
He has denied all charges, accusing police, prosecutors and the media of orchestrating a political witch hunt to topple him.
Alarmed by the prospect his right-wing bloc could fail to form the next coalition after two former allies joined forces against him, Netanyahu forged an alliance with an extremist faction inspired by the banned Kahanist movement, branded a Jewish terrorist organization by the U.S. for an extremist agenda that includes the forced expulsion of Palestinians.
Although Netanyahu's controversial political alliance and the corruption allegations have rattled many Israeli voters — and drawn condemnation from American Jews — it hasn't quite dented his personality cult. He remains admired by his right-wing, populist base.
THE FRESH FACE: BENNY GANTZ, FORMER ARMY CHIEF
Retired army chief Gantz burst onto the political scene just a few months ago, offering himself as an honest alternative to the scandal-plagued Netanyahu and his narrow coalition of ultranationalist and ultra-religious parties.
He joined forces with popular politician Yair Lapid, head of Yesh Atid party, and forged a new centrist party, Blue and White, made up of other former military officers.
The celebrated ex-general may be the only one who can compete with Netanyahu's own security credentials and gain the trust of a society that feels psychologically and geographically under siege.
Gantz has campaigned on his clean record and military pedigree, proclaiming that Israel has "lost its way," pledging to combat corruption and professing his devotion to state institutions that Netanyahu has assailed.
He has kept his platform vague, however, apparently aiming to reach broad swaths of political moderates. He talks about income inequality, rising home prices and the need for better infrastructure. He criticizes Netanyahu for stoking ethnic and religious tensions, and promises to amend the controversial nation-state law that marginalized minorities by declaring Israel the state of the Jewish people alone.
While trafficking in rhetoric of unity and egalitarianism, Gantz is careful not to come off as too dovish. He isn't specific about plans for engaging with the Palestinian leadership, wary of alienating political hard-liners. One tough-guy campaign ad bragged about the number of Palestinian militants killed under Gantz's command in the devastating 2014 Gaza war.
Gantz may be able to exploit Netanyahu's vulnerabilities, but it remains to be seen whether that's enough to oust the only leader Israel has known for the past 10 years.