I can't speak for MoO, but the thing about Stellaris, apart from the good tutorials, which makes it quite newcomer friendly is that it has a slow ramp; you aren't thrust into the thick of things. Like most other 4X games, you're quite limited in regards to what you can do at the beginning of the game, so you can take your time to absorb the available mechanics, and then new elements which are introduced via tutorial quests. The early game is a lot like Civ in that you're expanding and establishing colonies, and by the time you get to the mid game and really have to deal with other empires, you'll probably have a good enough handle on the diplomacy stuff to handle it.
Also, quality-wise, it seems that Stellaris is much better than MoO.