I entered the CF as a NES OP. It's an interesting trade with lots of room for promotion if you work hard. The great limiting factor in this is that it's an exciting job WHEN you get to actually do the job. Being that your job is electronic warfare, and fire control (weapons) you do bery little when alongside (docked in harbour). Likewise, when at sea, you spend a great deal of time manning the equipment but in a non-operational sense; again, this can be quite boring.
As for NCI OP, if you want to keep more mentally active then this would be a better choice when compared to NES OP. There is better alongside training through simulation for them, and they keep more active when at sea. Eg, things actually pop up on radar (NCI OP), while there of seldom something to shoot at (NES OP).
For what it's worth, if I was choosing a third choice (or even a first), I would want to pick a technical trade within the navy. Eg. Weapons Tech, Tactical tech, etc. If you're going to take the time to be trained, you might as well pick a career that can have some use when you retire.
Otherwise, as was mentioned previously, if you like working outside and keeping really busy all the time then Bosn' is your best bet.
No matter what job you choose you'll get pleanty of opportunity to travel all over the place once you get to your ship.
Good luck!