If you are a good Bard then you will be welcome in groups, as far as i am aware bards are still good pullers <unless they have changed it in the last week anyway. but if you want to ensure you can group then i would advise taking a shammy, slowers are very important in PoP and haste makes the world go around.
Besides shammies are fun to solo aswell
Rangers are uber dps in late game but there is alot of competion for the dps position in groups.
I would say take the class you enjoy most as it is the standard line when people ask thses sort of class questions but since you ask i think your guildlines for what you want point to shammy.
You could always roll all 3 and see how it goes
Bards: pulling and CC
Shammies: haste , slow , buff and a bit of DPS when mana permits
Ranger: dps dps dps and tryy not too get hit if posible <my wife also takes recponcibility for snares in LDoN.