For people from the US it's right that it belongs to the E segment.
I don't know why but we're at Porsche declared it to the so called C segment (comparable to the US E segment).
The Taycan will be part of the C segment. So therefore the direct competitor right now is only the Tesla Model S.
In the future following competitors will join the market:
-BMW i5
-Mercedes EQE
-Aston Martin DBX/RapidE
-Fiske Emotion
-Lucid Motors
...and many more in the next few years.