I'm not a huge corporate workplace kind of person, which is one of the reasons being an editor doesn't really appeal to me, but I also have to say that the constant moving and uncertainty career-wise would bother me. I'm not really into change.
Not that there's necessarily any certainty or assured stability when you take a job as a literary agent's assistant. You obviously are not guaranteed to become an agent, but once you are one, you don't have to worry about moving forward with your career by moving to different agencies. For instance, almost all of the agents who work at Writers House have been there for 10+ years. There isn't really any ladder to climb (or to jump from rung to rung) when it comes to agenting: You just go from being an assistant to being an agent (with possibly a between-point of being a junior agent, although not every agency does that).
Of course, instead of staying at one agency your entire career, you could opt to start your own (which is what Prospect Agency's president, Emily, did!), although you have to be pretty brave to do that! I got my job at Prospect Agency by reaching out to Emily (who was also a former Writers House assistant) and letting her know how much I admired her for going out and starting her own successful literary agency. The idea of tackling all the accounting, taxes, and finance-y things that come with running your own business is enough to make me run for the hills!
Me doing math.