Many people choose to form LLCs in their home state. This may save you money, because the LLC will not need to register as a foreign LLC if it does business in its home state.
If your home state has high annual LLC fees or income taxes, and your LLC does not do business in that state, it may be wise to form an LLC elsewhere. Doing business means more than just selling products or making passive investments in that state. It usually requires an office or an active business presence.