Between an LLC and sole proprietorship, my understanding is that an LLC creates a legal barrier between yourself and the business. The tax implications are the same. LLCs, from what I understand, especially a one-member LLC will just be pass-through (I believe you can elect differently) tax-wise but an LLC protects your personal assets from the business.

No one should really mess with C-corps or S-corps until they have someone telling them to. It's expensive and cumbersome to maintain one. Stripe Atlas is misleading a lot of young startups into believing they need a Delaware C-Corp immediately, when really it just benefits VCs not having to make businesses convert to those structures. If you aren't going VC, don't bother.

For instance, a C-Corp costs about $700 / year before doing taxes. An LLC costs about $30 / year.

A C-corp requires you to file monthly (or is it yearly?) minutes... which costs money to do... and you'll be the president, secretary and treasurer of. Then you have to fill out forms and junk (Stripe Atlas makes this easy but costs $).

An LLC on the other hand, you file a yearly report basically just saying "Hi, we are still around." and pay your yearly dues to your state.

Sole proprietorship is even easier. You just declare yourself as one. Like, just say "I am a sole proprietor" and boom, you are one. No filing required (Check the state, I am sure some are different). You can file a DBA (Doing business as) with your state treasurer and still be a sole proprietorship.

To be honest, an LLC is probably the safest thing to do in the long-term but short-term sole proprietorship is fastest.

The thing that I do is have an all encompassing LLC that I run all of my projects under, rather than having a new structure for every business.