WP is usually preferred to be specced as a backline AOE/Group healer for organized warbands in Forts and Cities. It's still possible to spec as a damage dealer or off-healer for scenarios and general RvR, but most warband leaders want WP to be dedicated healers in Forts and Cities.
For BW, I believe the preferences is usually AOE/Bomb specs for Forts and Cities.
I don't know that there are any specific classes to avoid (maybe WH), just that certain specs are preferred (like WP as full healer).
Both BW and WP are needed on Order, but are also well represented. Other classes on Order that are needed but less represented include:
- Sword Master
- White Lion
- Slayer
- Engineer (with Magnet)
- Run Priest Rune Priest
EDIT
Oops hit submit too soon.
Sadly NA primetime isn't the most populated but it is still playable (between 500-1000 people online generally). EU Primetime is the most populated (1500's). For organized groups on Order for NA primetime, I'd recommend groups like Fog of War, The Holy Kings, Reforged, CNTK, Rescue Team. Note: some of these have recently changed their requirements to CR 40. I'm not sure on Destro who is really running during NA primetime. Destro is very strong in EU primetime.
EDIT 2
This weekend is 2x XP and Renown weekend, so it's a great time to jump in a level up a character. There should be a lot of people playing as well.
