Based on what I do now, either a professor at Starfleet Academy or whatever other universities are still around, or something in a casino. Being an agent with the Federation Gaming Control Board might have its challenges.
Are there still universities besides Starfleet Academy in the Trekverse? We saw that Cambridge (or at least the Lucasian Chair) is still around in "All Good Things," but what about everywhere else? I'd guess that with the "we work to better ourselves" ethos there would be a thriving adult extention/continuing ed sector.
Even hypothetically, I'd want something that let me spend plenty of time with my family, which is why the college route sounds good--no starships for me, unless I can be in home for storytime.
If I had to choose something on a starship, it's probably be swing shift security supervisor or something like that--enough responsibility that I'm not slacking, but not a gig where you're on call 24/7.
Being a Prof would be great. What to you teach now? (I'm inferring that you are indeed a professor.)
But you're in luck. There are many educational institutions in the Trek future:
* U of Betazed, Bajor, Alpha Centauri (I'm sure there are others on other UFP worlds. eg, Bolarus or wherever the Benzites live. And the latter are supposed to be highly intelligent.)
* Stanford and Texas (in the Enterprise era, at least)
* Daystrom Institute (
the top-flight place)
* U of Mississippi (mentioned in the TOS era. If that's still around in the 23rd century, there are probably plenty of Earth schools that still exist, in addition Cambridge. After all, some of those European schools go back over five hundred years, and some East Coast US schools are around 300 year old)
* The highly prestigious Orion Institute of Cosmology (the arrogant math whiz crewman Harren had wanted to go there but was stuck in the Delta Quadrant)
* The Andorian Academy
* Vulcan Science Academy (might be tough to get in for a non Vulcan)
* The highly-regarded Regulus III Science Academy
* And the many, many colleges, divisions, academies, campuses, etc., of Starfleet
Then there are the many non-friendly institutions, such as Romulan and a whole lot of Cardassian schools (there's even a Cardassian Institute of
Art!). In the distant future, there's the UFP Copernicus University (29th century I think).
I say all this because, if weren't on a starship, I'd definitely be teaching. The
only reason I'm going for a PhD is because I have the teaching "bug". I've loved every opportunity I've had to teach. Unfortunately, in my field (electrical engineering), it's tough to get a teaching position without a PhD or an MS and a lot of distinguished industry experience. And I don't even want to be a research prof--just teach! Should have chosen physics, math, or stats--much easier to get into teaching. (How many schools have engineering colleges? Answer: not many.

)
Oh well; the research I get to do sometimes is interesting...