I highly recommend skipping straight to witcher 3 unless you really love the series and want to consume everything it has. Still, 3 + the dlc has a lot.
TBH my favorite part of W3 was all the side quests. The writing and dialogue are intriguing and give you more of a flavor for the dark fantasy of the world.
I was looking forward to cities 2. When I heard it had crippling performance issues, I decided to wait. Still haven’t gotten back around to it. There are just too many other games that already work for me to put up with broken new releases.