Rogue.
Nah actually I think DH can be funny, the damage output is surprisingly good for both specs though you can't solo with the DPS one, it's only for questing. Tank spec has decent damage mitigation, decent in-combat healing and both specs have speed with their Mastery
If you go Night Elf you have the all-important Shadowmeld.
Infernal Strike is the best vertical mobility avaible to f2p and arguably the best one period. With 12 sec cooldown, 2 charges and a good range it honeslty allows for a lot of fun when exploring.
Overall it could be a bit challenging every once in a while but a really funny playstyle.
The big downside is : you can't be a Tauren so why would you play that
?
Either way Shaman is cool but you can try to solo as Enhance or Elemental, both are viable although you'll have to be careful. If needed you have the Resto spec to fall back on.
Same with Druid, Resto soloing is fun and you have Guardian as the safe spec. Plus having Stealth is neat. Also both those classes can be Taurens (okay I'mma stop my propaganda).
Anyways if you go DK you've got balls of steel and a lot of time to kill.
Final answer, I kinda want to say Shaman but you already main this class so prolly DH that's quite a fun playstyle.
Also, my respects to our fallen comrade, may his successor be luckier or less ambitious with his preys