I enjoyed FO4 a great deal, warts/glitches and all. I’m on my second playthrough because I’m just not ready to leave it yet.
Far Harbor received a number of good reviews, so I added it, but found I didn’t really like it all that much. Actually, it was rather dreary, even for an apocalyptic world. I’m ignoring it on this round. However, you really can’t ignore it when you’re doing radiant quests (building xp to level up) because those quests try to send you there on occasion. I might uninstall it and see what happens.
Nuka World was okay, even somewhat interesting and fun in its missions; at least you get an effective weapon and its variations from the factions, and better standard armor (and some opportunities for unique, if not necessarily improved, power armor).
I wish the companion aspect was a little more robust, especially as you advance in a relationship. For example, after you romance a companion, they say endearing stuff to you but you can’t respond in kind; you just have the same stock replies that were available before the so-called “romance”. It wouldn’t take too much to make those interactions a bit more satisfying - some level of interactive responses based on intimacy level with the companion.
Also, maybe a little more work on companions’ awareness of each other. If two companions are competing romantic interests, it would be nice to build those interactions out a bit more. Again, it needn’t be too complicated.
I come to this as a female in real life, so the relationship component would be important to me. 
As for the rest of it, I enjoyed most of the missions, the strategizing, the weapons and shooting up enemies, not to mention calling in vertibirds. I love the exploration factor and the surprises of open world shooter games.