I think filing for an S-Corp would be your best bet. You get to enjoy unlimited liability while also having the same tax benefits of an LLC.
LLCs are often better for businesses with more than one member. Since you are the only member, S-Corps are probably a better bet. Additionally, it is a lot easier to sell shares of a corporation (non-voting shares) than to sell % ownership of an LLC when seeking funding.
By incorporating, you automatically get an EIN/Tax ID since a corporation is considered a separate entity.
In regards to building corporate credit,
here is an extremely helpful link.