Difference between S-Corp and Sole Proprietor taxation in an LLC?
In short, one of the main differences in having your LLC taxed as a sole-proprietorship as opposed to an S-Corp, is that by electing to have the S-Corp tax structure, you would gain certain self-employment tax benefits.
There would be a few limitations the LLC would have to comply with if it elected to be taxed as an S-Corp, such as not being able to have any members who are non-U.S. residents, as well as not being able to have any corporations or partnerships as members.
The amount of members may make a difference, depending on the intentions of how the profits would be shared and such, the type of members in the LLC, etc. Typically, when an LLC is owned by one individual, it's considered a single-member LLC, and by default taxed as sole-proprietorship/disregarded entity. When there are multiple members, the LLC is generally referred to as a Multi-member LLC, and by default taxed as a partnership.
Being there are many caveats to all the different possibilities, it would be strongly advised to consult a licensed accountant familiar with the S-Corp tax structure to find what would fit your business plan the best.