I have owned two Speckled Sussex, my second is from last year's batch. Both have been without personality. They both sat, sit, around a lot, and generally are quiet placid birds that don't lay well.
My Ancona are a bit more active and curious. I wouldn't call them flighty, just aloof, and independent. They aren't meek, they talk a lot, and forage well. They also lay well.
So I personally will never get anymore speckled Sussex due to them being blah. Ancona are animated and take care of themselves. I'm sure if I actually handled my chicks they would be even more friendly.