Given your description of needing the best of everything, it could be either the scapegoat or sometimes the GC. Sometimes the GC is aware there is a bottomless gap just under the very fragile floorboards he's walking on and wants the best of everything as proof he's the more favoured.
Other GCs have been so consistently favoured that they really don't feel insecure and are certain they deserve everything. Total delusion.
Some scapegoats sink their lives into trying to earn parental approval and never worry about material things. Others try to get the best to prove they really are high-value and should be loved, or material things replace genuine love.
It's puppies who are lived, well treated and given good reliable boundaries who grow up most secure and happy, who look outwards, knowing they have a secure base. The ones who have been given small tastes of love but mostly rejection are the ones who keep coming back and back trying go get more of that wonderful live and attention. The utterly rejected sometimes turn vicious, or have no trust in humans.
We aren't much different.
A few scapegoats and a few golden children manage to break free. There are a few people on mumsnet who have done that. They've sometimes even managed to keep good relationships with their sibling(s). The sibling relationship is often very badly damaged where the GC / scapegoats dynamic exists.