I enjoy eu4 more. It's much more of a macro game, even if less detailed. CK2 just gets extremely frustrating with many of its "features" and overall limitations.
The way of life change is ALMOST the greatest patch ever, but the ability to just kidnap fools with no consequence is basically game-breaking to me, and the seduction system seems to be some kind of horny nerd fantasy where literally anyone will sleep with anyone, regardless of charm or personality, based entirely on frequency of pestering to do so, to where any kind of relationship role is meaningless next to the awesome power of sleeping your way into a plot to kill network or bastard claims. Then there's blob stability, which at this point it seems that eu4s coalitions somehow manage to keep blobs in check actually better than eu4s internal mechanisms that should never lose this one.
Eu4 on the flip side is way less involved and basically a war game. Personal interactions are moot and peacetime is a snorefest, but that comes with good and bad, since you can just focus on what seems to be done mostly right (conquest) and play it as a war game and enjoy it as such. Basically, eu4 is a war game and does it pretty well, ck2 is a dynasty builder game that's only really good as a war game, but not eu4 good, and its core dynasty mechanics at this point are more of a drawback, even if they're more fun than doing nothing while at peace.
Play both. Don't be cheap.