It does not matter which color you choose.
Color does not affect the personality.
the color of a parakeet barf are ussually green white gray white
A male parakeet has a blue nose above its beak.
pink...brownish color
Color can be either sex, but they have feathers, not fur.
In captivity, the domesticated Indian ring-necked parakeet has undergone a lot of selective breeding that has resulted in color patterns that aren't seen in the wild birds. Humans have bred the birds to select for different color combinations.
Presuming that 'parakeet' means budgie, even though there is actually no species known as a parakeet, the cere, which is the part above a budgies's beak where their nostrils are, is bright blue on a mature male budgie.
Hybridization or induced mutation
If, by "parakeet", you mean any of the smallish parrots with long tails, such as budgies or cockatiels, then no, it most certainly does not have to be the same colour.
not exactly, it is just the color
I would personally say the red ones are the nicest looking.
Nicest
No. Nicest is an adjective.