It's worth pointing out that while accurate when applied to Israel, "apartheid" suggests a false equivalence in the sense that Israel's crimes are far worse than anything the National Party ever did in South Africa.
By way of comparison, the Sharpsburg Massacre, an event which shocked the conscience of the world, killed 69 and wounded about 180; by comparison, the least deadly of Israel's punitive rampages in Gaza, 2008-9's Operation Cast Lead, killed nearly 1,500 Palestinians.
The insane criminals and terrorists currently in charge of Israel are not liberal by any stretch of the imagination, but even if we accept the premise that Israel is a liberal state (I guess it technically still has elections and stuff) this amounts to a devastating indictment of liberalism rather than a reason to support Israel against its "illiberal" opponents. Indeed, liberals often appear to take the position that illiberal regimes are bad because they do things like suppressing freedom of speech or annihilating tens of thousands of people, but when liberal states do these exact same things there always seems to be some excuse or justification.
As far as I'm concerned saying we should support Israel in spite of its hideous, unspeakable crimes because it is "the most liberal state in the region" is just very thinly-veiled white supremacy and Edwardian-era imperialist ideology. Israel being "the most liberal state in the region" is not a reason to support Israel's crimes, it is a devastating moral indictment of liberalism.