Remember that as a junior officer you will get one chance to be a JEngO, and there are only 2 JEngOs per Sqn (normally) then as a Sqn Ldr you will have another chance (If you are really lucky) to be a SEngO (One per Sqn). So not many jobs left!
However there are alot of stn jobs which are not all bad. I have had 2 stn tours both of which have been great fun and I am now a fast jet JEngO. I certainly enjoyed my stn tours more as I had more time to enjoy what the stn could offer, but as a JEngO the job is alot more rewarding. I have yet to experience the wonders of a staff tour (Boo) but I have to get signed on first...
I would suggest deciding what you want from the RAF, you'll be stuck with it for quite a while!
Remember the careers office has a job to do, so be on you guard!