All of them are suitable for low level play. What really matter is the type of character you want to play and to a lesser extent your level of rule mastery.
The druid is a prepared divine caster with a lot of situational special abilities. They have a large spell list that is incredibly versatile, but doe require a lot of planning. It is quite easy to get caught with the wrong spells memorized. They can convert any spell into a summoning spell but that also means you need to be familiar with the creatures you summon. In the hands of someone familiar with the material they can be quite effective at any level. In the hands of someone who is not familiar with what they can do, they can be a huge delay. Even the animal companion can cause a delay if the player takes too long to figure out what they want to do with it.
The Oracle is a spontaneous divine caster so they have a very limited number of spells known. But they don’t have to worry about memorizing spells, they simply have a number of spells of each level they can cast and can cast any spell they know with those slots. They also have a special abilities based on their mystery and curse. Those are usually pretty straight forward you only have to worry about learning the abilities you actually have. They have the same spell list as the cleric so a lot of their spells are buffs and support spells. They have a few offensives spells and many of those are tightly focused. Vs Undead and outsiders their offensive spells are usually pretty good. Vs most other creatures their offensive spells are less powerful than those of a wizard or sorcerer. Most of the planning of the oracle takes place when building the character not during the game.
The Shaman is a hybrid class that is basically a combination of witch and oracle. They are a prepared divine caster, but their spell list is not as large as the druids. The other two classes have such large spells list due to the fact they have been around since beginning and each new book added spells. They do get hexes so that usually means there is always something they can do in combat. The wandering spirit allows them great versatility, but does mean you need to be familiar with more of the rules to take advantage of it.