Necessary Hardware Units

I'm trying to assemble a studio plan so I can plan out my purchases over the next few years. What are the necessary pieces of hardware that one should have? Like LA2A, 1176, 1073, etc.

I'm not talking about "one unit to do multiple things", either, I mean, if I one should get both an 1176 and a Distressor, even though they cover much of the same territory, then please say both of them. I'm trying to make a comprehensive list of what covers most scenarios I will encounter.

I'm also trying to stay genre-neutral, but if your suggestions lean heavily in favor of a specific genre, that's awesome, but please make note of it!