which expansion pack includes the most/best build-mode items

@elulu8 it really depends on how you like to play the game.
Out of those you suggested, I'd suggest looking more closely at Tiny Living, Seasons, Discover University, Get Together and Eco Lifestyle (solely based on my style of game play). They have some really neat items which can be used across multiple styles of game play.

I'd suggest checking out which items you'll get with which packs:
https://www.ea.com/games/the-sims/the-sims-4/pc/store
If you click the above link, then click on an individual pack, it will list all the build/buy items that come with that pack