I wish the metal modular corner prefabs didn't bow outwards.
It leaves a distasteful gap between itself and adjacent walls, plus you can't put any decorations on it without them clipping/floating and looking ugly as forget.
Also, picking up items via the settlement manager is nicer than trying to move them by hand, however it wont let you place things on shelves properly, instead snapping to awkward places or even inside the shelf itself.
It just makes the wide range of shelves useless if i can't place anything on it without usingt he equally glitchy FO3/Skyrim system of doing it by hand.
Settlements are a lot of fun, but the snapping system and a lack of fine-tuned movement, plus some awful collision boxes can make it infuriating when you're trying to make a home you want to live in.
Also the fact that you get half resources for breaking something you made down is stupid. I can't tell if an object will fit properly before I make it, so when my design doesn't work out it punishes me for experimenting.