Personally I've found Blacksmith to have some pretty good quest to it. If you love Ishgard as much as I do the 3.0 quest are a must, it's one of my top 3 all time favorite quest and I'm really hoping the person you worked for will appear in the upcoming rebuilding Ishgard thing in 5.1 or so. She was such a great person and Ishgard needs more people like her around. The 4.0 Blacksmith quest is also pretty good, the ending earned a big laugh out of me while over all being a pretty good quest chain in general. Haven't had much of a chance to work on BSM in 5.0 yet, but the role quest start up seemed pretty decent.

Aside from this I would have to say The 5.0 tank role quest. It's probably the first quest I got to do on my PLD that felt like a real PLD quest. I'd go so far as to say I liked the tank role quest more than the MSQ...*is murdered to death by thousands of rabid FFXIV fans for this comment*.

And lastly I would say DRG. While the stories aren't anything to write home about, there is a DRG NPC in the MSQ around late 2.0 into early 3.0 that will talk differently to you if you've done them. As such I always keep them up to date and finished second after my main job of PLD just in case it happens again.

And that's my 3 picks.