Admin - hard graft, very office orientated and generally unappreciated by the rest of the mob. But can open up some spankingly well paid jobs outside.
Who'd have thought that an admin job would be so office orientated?
Micky take aside, it is also offers the quickest and easiest commissioned promotion opportunities of any of the branches if you decide to stay in rather than jump to an outside job. I know a number of adminers who fully expect that as long as they are doing a fair job and keep their noses clean, they can pretty much guarantee retiring as Gp Capts. Sad thing is, they're probably right. But remember, despite all the blah about all jobs above Wg Cdr being on a common list and awarded to 'the best man for the job', the reality is a bulletproof glass ceiling for all branches except Pilot.
Flt Ops hasn't been mentioned above. It is currently a very disjointed specialisation with little identifiable career structure and therefore vastly variable prospects for individuals (ie from poor to bloody awful for most people just the moment, although a couple of individuals seem to be doing enexplicably well!). Jobs range from the very interesting, high tempo and utterly ops focussed (more so than many of our aircrew on flight decks if truth be told), to the utterly banal backwater rubbish. It is still relatively early days and the specialisation is maturing, but until there is a better standardisation of posts and a sorting of career paths, little will improve. Whether this is the right time to join is hard to tell - it could be the ideal time to catch the wave that will benefit from a re-org and the fact that there are so many hacked off opsos leaving in the next couple of years that feel that they were completely mis-sold the specialisation. These gaps could provide the ideal opportunity to get in on an excellent, interesting and varied career. Job opportunities outside after Flt Ops are very good. I am aware of one Flt Lt opso recently offered an excellent job high up in an airline - higher up the chain than than they were willing to put a Wg Cdr pilot starting with the company at the same time!
Oh, by the way. I wouldn't count on the FCs keeping loads of seats in the back of the E3D - surplus F3 navs will need to go somewhere and the FC world has been shooting itself in the foot by stating that they don't consider the E3D to be a front line tour. Whereas hiding underground in Norfolk is! If the posts aren't core business, they are easy to take away...