I'd go C-130 because of the sheer number of different things it does - Low Flying, Stores Airdrop, Paradrop, Unprepared Landing Zones, Search and Rescue, AAR, Maritime Reconnaissance - all day and NVG. Oh and it also does routes round the world.
I originally thought C-17, but it turns out that it is only used as Strategic Airlift and has no tactical or real 'military' flying in the RAF, just hump stuff from airport A to airport B.
Factor in that to get from A to B in a C-130 means you have to stop over in a lot more places and see a bit more of the world instead of just taking off from Brize and landing directly at destination.
A400M after a good few years in service will get some similar capabilities as the C-130, it definitely won't be doing anything remotely interesting until good ol' Qinetic/ Boscombe get their teeth into it. So just repeat what I said about C-17. Oh, and you're having a giraffe about SF, right? Have you see the size of that thing?
Number two would be 32(TR) Sqn on either HS125 or BAe 146. Again the variety of routes is huge, NOT just Europe, and you do get some time in theatre doing something
vaguely military instead of being a corporate jet all the time.
10 Sqn, Voyager, I (personally) would consider as a last tour, only to get some fan time and Airbus Flight Deck. I can't say the tanker job particularly appeals to me but maybe as a crusty old Captain who's ready to leave I could do it for the A330 TR! Along the same lines is the Global Express type rating of the Sentinel on 5(AC) that makes a recipe for some serious moneymaking outside of the RAF.
ISTAR platforms in general are not going to have exciting flying and I heard you end up walking around with 5 degrees of left bank when you come back from a particularly long sortie.
Sentry, I don't know much about but I'm not sure they're taking people anymore?
Shadow is similar to Sentry/ Sentinel, but with a King Air. Though much like a fighter you are squashed into your seat with the amount of stuff you're wearing but have the added pleasure of being almost literally shoulder to shoulder with the guy next to you and unlike other ME aircraft you can't easily get out of your chair to use the facilities!
I know literally nothing about the RJ and the Islander/ Defender is Army!
Obviously this is all tongue in cheek and is my somewhat cynical opinion, but If you joined the RAF to flying something military in a military fashion the C-130 and eventually A400M are the only real tactical ME aircraft. The rest, whilst doing a military job, are not tactical in the slightest with the exception of the C-17 doing occasional steep descents and 146s doing route detachments in Afghan.
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