Personally I feel Starly and Pidove are the worst regional birds. I hope the regional bird for the 6th gen isn't fat and black/grey.
Taillow is my favourite regional bird. If the upcoming games don't have a regional bird of their own I hope they use Taillow/Swellow as the stand in.
Starly isn't all that bad throughout D/P/Pt, especially since it gets Close Combat as a Staraptor and learns some strong attacks.
I hope the new regional bird is useful throughout the game like Starly is.