What percentage of design, marketing, ux, ui, security, speed, accessibility, etc.. should I aim for in the first iteration I ship? What have successful products found to be the priority factors?
There is no percentage. Before you ship a product for the first time, it should do what is supposed to do. For example a todo list should be able to manage tasks. If it does that you can ship. Is it speedy, may be not, that is not essential.<p>Identify your core offer (easy to use todo list). Once you cover it you can ship. Everything else (marketing, security etc) can be done afterwards. + In the mean time you will gather feedback.