First of all, he should physically look exactly like Dante, as identical twins. His hair should be black as well, but with another hairstyle, maybe longer hair that is swept back like Loki's from The Avengers movie. I would like for him to wear a white shirt with a blue tie, black dress-pants, a pair of brown leather shoes, brown leather gloves and a black leather longcoat with blue accents and golden design on.
In his hand he should hold Yamato, but instead of looking like a traditional katana it should have some demonic influence on its design, like Rebellion has.
Personality wise I would like for him to side with the demons for personal gain, using them for his own purpose OR have him become a puppet replica made to outmatch Dante, somewhat like Nelo Angelo was in DMC. He should have a cold and emotionless demeanor, like in DMC3.
I have never seen Vergil as some tragic hero, but more as a cold and calculative man who doesn't care about anyone else but himself and his own personal goals. He is ready to sacrifice others lives, even innocent people, just to get what he wants. He hasn't always been like that, but has become that after the death of their mother which in the end have him be egotistical and evil. And I would like that to be translated into this new Devil May Cry as well. ^^