I finally started playing CK2 again the last couple days. It's fascinating stuff, but I freely admit I wouldn't mind a tutorial that completely held my hand through the first couple years. Talk about your steep learning curves (and this is supposed to be one of Paradox's more accessible games?!)... 
Actually, i think it's one of the most complex games, at least, that's what i remember from playing the first one. I would say Europa Universalis 2 and Stellaris are the most accessible. I have a lot of respect for Crusader Kings 2 and will take the time to learn.
I agree Stellaris is probably Paradox's most accessible game (at least of those produced in-house). I do think the changes in the 2.2 update needlessly increased the learning curve, but it remains relatively easier to get into.
I can't comment on EU2, as I don't own it. I do own EU4, however, and some day I plan to tackle that one (although at the rate I'm going, I'll probably be retired before I get around to doing so
).
