pbb in general are worth the money.
You get more support slots thus more sailors can lvl up simultaniously.
You have in general more range than equivalent bb1-2
Most of them are faster more durable and more agile than their counterparts (again bb1-2)
km/rm pbb get a nice aa gunnery. uk pbb is a beast at higher lvls. us/sn are pretty good in general especially to get out of allaska/tenny and be able to move up faster.
hope this helps.