What sets Omnisphere apart from other software synths?

I'm looking to buy a new software synth. I think the Datamind synths Combobulator and Concatenator look interesting, but they're super expensive. I could get Omnisphere for the same price. I have other synths like Serum, Arturia plugins, and Massive /x. I was just wondering what sets Omnisphere apart from everything else. The others are more experimental.