Interesting vs tractable PhD topics When one starts a PhD, should it be based upon interest or tractability of the project? If a project fails is switching advisors a reasonable option within the same department?
I have a couple options for PhD, one is an area I am more interested in but it's a more open ended problem with potentially less straightforward solutions. It also gives a background in more areas I am interested in learning and more industry applicable(focused on making novel system which works).
The other I don't think I want to work on for 4 years but probably will be more straightforward, it's also less useful to industry(I think) and more theoretical in nature. It is a continuation(mostly) of what I already know.
I'm not sure what to do, I have no interest in staying in academics so a PhD which is more focused on an applied topic which could be used to spin up a company is a lot more interesting to me but I obviously don't want it to fail.
You give a false dichotomy, because you should be doing a project that you are interested in and one that can be completed. There's no point in choosing a topic you hate working on for 5 years but is solvable just as there's no point in choosing a topic you're passionate about but not even those who have studied it for decades could solve (possible, but highly unlikely). Therefor, the answer to your question is to choose a solvable problem that you are interested in.
However, if you're interested in living in a binary world, then choose a project that is tractable and you hate. If you are concerned about getting a PhD, then it's better to complete a project and receive the degree than to work hard on a problem and receive no degree.