Forgetting who you are, or why you are there will hold you back. As an ET radar (ETR), I had to compete with other ETRs for advancement. So you come out of A school an ETR3, having been trained on only one radar, (SPS-10 in my case), then on to a year or so of nuke training. So while in nuke school, you have to also study for the ETR2 test, again theory and radar specific. If things go right, you leave nuke training, and you report to your ship, walking aboard as an ETR2. Now while you qualify as an RO, standing watches and doing all the other maintenance and such, you have to study for the ETR1 test. ETR3 was easy, ETR2 was easy, ETR1, not so easy, as you are now being tested on equipment you have never seen, and concepts you have not used for the past two or three years. The same challenge for the ETC's (ET communication). Now I know, more points are given to nuke ET to help advancement, but you still had to pass the test.
E-6 is a comfortable place to be as a nuke (there were a lot on my ship), to high in rate to do the dirty stuff, and low enough to not have to deal with the division bs or be required to qualify as a watch officer. This is not true in the conventional fleet, where as an E-6 you are in the midst of it all, if not at the fore front. E-7 is where a lot conventional ETs liked to be, the field narrows as you move to 8 and 9 as the lazy or non-motivated drop out.
Even as a trained nuke, the Navy looks at your nuke job as an assignment, to the Navy, you are your rating. Or at least that was the way it was back then.
Now back to the person who started this thread. Your question comes down to two. What rating pays the best and housing for your family at each of your posts. If you are only into this for the money, you will not be content. The hours are long and expectations high, the demands are always there. It is hard enough for a father to miss his children's birthdays, first day of school, or winning their first soccer game, or to not be there to tend to a sick or hurt child, or to comfort his wife when she is down. I can barely imagine what it is for a mother to miss all of that, and my hat is off to those women who enlist and their husbands who have to be mother and father (and mothers who have to be both).
Keep in mind that sailors serve on ships, and the ship always comes first. The Navy will own you lock, stock, and barrel for six years. You will do what they say, go where they say, when they say, and for how long they say. If you think the extra money will offset this reality, then go for it. If not, stay out of the military, or join the Air Force.