See:
"Twelve reasons for a startup not to be an LLC" - Joe Wallin - Startup Law Blog (September 30, 2011)

http://www.startuplawblog.com/2011/09/30/12-reasons-for-a-st...

Best advice is to spend a few hundred dollars and talk to a Certified Public Accountant for about two or three hours. I hope you have people in your network of friends, parents, collaborators, legal advisors, potential funding individuals, chambers of commerce, business development collaboratives, and the like that can send you to a friendly CPA. If you do not, you need to develop your own network of advisors, today.

In brief: A Limited Liability Company (LLC) can ELECT with a filing to the Internal Revenue Service to be treated for tax purposes as a partnership, or as a C-Coporation. A limited partnership needs to have one partner that is a "general" partner that has unlimited liability, who then associates with limited partners, and that makes the whole structure more complicated, if you choose to make a corporation a "general": you then have two entities to manage. A corporation can also elect, by filing with the IRS, to be a Subchapter "S" corp, which has many characteristics of partnership taxation, but also numerous cautions that must be monitored to avoid running into unexpected tax issues.

In general, if you're expecting funding from outside sources (which could be you, the founders), you'll find that a standard C-Corp setup is what the funders prefer and desire. Generally Venture Capital funds (which are typically structured as limited partnerships themselves), and individual investors do NOT want the activities of a funded startup to start showing up on their own personal tax return (which is how Sub-S, Limited Partnership and LLCs that are treated as partnerships work for tax purposes) except in a particular limited and defined way (which is more typical for Real Estate projects). For example, if and when your entity starts being profitable, do you want to start paying taxes on profits of the LLC, that the LLC may not be able to afford to distribute to you (so that you can pay taxes)?

And LLCs have enough control and valuation wrinkles, that it can be simpler to do a corporation form of entity, from an investor's perspective. It can be, in some cases and states challenging to have more than one class of LLC owner/members, whereas Corporations typically have more than one class of stock.

You fail to indicate why taxes are an interest, so it's not really possible to respond very well to your inquiry. Just talk to a good CPA.

I would speculate your main interest is to support your work, with some kind of funding, and figure out how to get something valuable to a newly found or newly created market. Why are taxes worrisome as this stage of your effort?

There's not much point in capitalizing your startup costs, since you're probably not going to make money for a while, and a lot of effort will be thrown away as you figure out what you're going to do...and that makes it interesting to justify and characterize the capitalization of the effort. It is likely the ultimate actual product you produce might only have a fraction of the expenditure-to-date located the final result...after you throw away previous efforts thanks to pivoting and re-thinking what in the world your market and product is.