The tutorial in Endless Space 2 walks you through every screen and only pops up when you’re at a new screen. It really comes down to a personal preference, both games provide hours of fun. For complexity and a game that lasts virtually forever, Stellaris would be the choice.
If you like a game that can sometimes be completed after 100 turns or so and like a little more control over space battles, plus one that has more of a “space opera” flavor to it then Endless Space 2 is better.
But how does it compare to a game like Stellaris? They left behind a material known as “dust,” a near magical substance that’s highly valued by all empires. The Endless universe is one where the “Endless” once dominated the galaxy, but for reasons unknown they no longer exist. Endless Space 2 is turn based and set in the Endless universe.