Orianna has a very safe lane where she just sits and farms. Her late game is incredible tho, she can 1 shot a carry if she gets her ult off, and her team fight potencial is very good. Syndra is massive lane bully, but unless gets kills early, she doesn't scale that well into late, cause she has 1 stun ( if you aim well) she will always have to spam her Q in a jungle team fight, cause most times there are no minions for her abilities, but getting the ult on a carry could remove him from a fight ( But it is not like Ori's ult that can hit more than 1 champ, and Syndra's is more predictable) Anivia is a lot like Ori but is a lot harder to play and you need to have blue buff pretty much all game (Mana cost is insane if you do not watch out). Ahri is the safest pick, ok laning , good damage late and good team fights. She is a assassin and has good damage, but no real aoe. My buy would be Ori. She can easly kill more than one champ ( Syndra uses her skills, kills one ,then getting more kills is not that easy) she is the only one of those champs that has a shield (Not only for her, but can be used on her teamates as well) and can wombo combo with great ease.