Pretty much the only reason I can get behind forming a C-Corp is if you know there will be investors coming on board sooner than later.

Corporations have so many governance requirements and taxation issues that LLCs simply don't--management by an appointed board of directors, president / secretary structure, taxation on shares (rather than on income--though this can be mitigated / reduced), etc. LLCs can be managed by a manager or members and . . . that's about all the governance they require.

Forget Partnerships altogether.