[Shodo]

Soloing - Shaman, Bard/Druid (excluding kiting, both bard and druid can charm kite - druid can root rot (but not well), bard can fear kite and many other things).

Grouping - Bit of a wash for all three depending on the level you're talking about. Definitely Shaman or Bard at higher levels would be more in-demand (slows/buffs for Shaman, pulls/CC/etc etc for Bard). Early game I don't think there would be much difference - maybe a bit more toward Bard still.

Power at end-game: Shaman first for sure. Bard/Druid I'm not terribly certain on which would be more "powerful," if you're still excluding kiting. Druids get ports, bards get more versatility and shinier armor.

Added - money-making potential at end-game: All three are great money makers, but there are some differences.
Shamans get big bucks by soloing/duoing tough cash camps that a lot of other classes can't handle. Great money, but probably less "casual" as it often involves being online for extended periods of time.
Bards can make a killing off power-leveling - might be wrong, but I think Bard PLs are typically the fastest.
Druids can also make a killing off power-leveling - I think they're a tad slower than Bards as far as exp/pull (again, I could be wrong), but they have the added benefit of being able to toss out buffs to nubs at the tunnel and ports (can easily make 500+ plat per hour very casually just porting people around).

Tldr; (In general terms) Shaman most powerful, Druid most casual, Bard some where in the middle & more versatile than either.