by Dormammu
Pragmatically, the best things you can add are retail products. The two previous core sets provide the most varied content and so they are great additions. After that, the season 2/4/6 boxes are second best.Everything you listed is more marginal. I’d be tempted by the extra cards simply because they’re very inexpensive, but Scarlet is totally not worth it given how many investigators are available in general. Godzilla is something of a novelty as well. Old KSE boxes are more expensive than the value they provide.
The only caveat to this is whether you’re the sort of person who likes to get everything for a game and might want to “complete” it later. If so, this is the cheapest any of those items will ever be.
But practically speaking, “everything” is more than you need. The best value is definitely a core pledge and retail content to taste as you play the game going forward.