The most compelling argument I've heard: The antichrist will believe he is doing God's will, but through a web of twists and lies, he is actually following Satan.

And the beast is Islam. This was a common assertion until the Ottoman Empire fell. From there, western scholars began looking elsewhere, forgetting that Revelation says the beast will be wounded, fall and rise again.

From Walid Shoebat and Joel Richardson's book God's War on Terror, Islam has its believers following what they think is God, but in actuality they fight against the Jews and Christians. Their prophesies of the end times are very similar to those in Revelation, but with the outcome of the battle reversed, ie Jesus returning to proclaim Islam as the truth and destroy the Jews. Baghdadi fancied himself as the Mahdi (which has the same characteristics as Christianity's antichrist), set himself up as the spiritual leader of the reformed caliphate, and nearly got there until he took a JDAM to the face.

So, in this scenario, look for the reformed islamic caliphate under a single ruler and their mahdi who deceives the world to follow them.