Here are my current favorite curriculum companies, in alphabetical order.
Beautiful Feet (affiliate link. BF does have some religious content, but contains warnings as to which materials, it also has secular book bundles listed under the charter option)
Blossom & Root (nature based secular homeschooling. currently obsessed)
Bookshark (Eastern Hemisphere is especially fantastic. “faith neutral” curriculum.
Brave Writer (curriculum & online classes A+)
Build Your Library (LOVE!!! This is an excellent choice for kids who love the literature based approach aka lots of reading differing books)
Chistopherus Homeschool Resources (Donna is an amazing human being. Real Waldorf. Amazing. I aspire to do Waldorf the proper way in large part because of her & her company.)
Gravitas Publications (REAL Science 4 Kids)
Latin for Children (Classical Academic Press. Also recommend their Song School Program. Some religious content, such as Christian terms– very few– we skip over. Best Latin program I have tried/seen.)
Oak Meadow (Waldorf-ish, though somewhat common core aligned. Great choice if you’re looking for the structure of a text book but the content of a homeschool curriculum.)
Pandia Press (History Odyssey & More)
Rosetta Stone (foreign languages, immersion based)
Thomas Jefferson Education aka Leadership Education — this is more of an approach than a curriculum, per se, but I HIGHLY recommend checking them out. We gained a lot through their “This Week in History,” and I personally benefited from Mentoring in the Classics.
The Well Trained Mind (Peacehill Press; Story of The World, etc.)
Zaner Bloser (we use handwriting & Grammar, Usage & Mechanics aka GUM)
I will circle back if I suddenly realize I have forgotten something, which is often the case!