I'm trying to consider if its a better idea to start fresh for this new content, or play one of my existing characters?

For the best possible experience out of the expansion, what is reccomended? New character, or twist my role-play to bring an existing character in?

I have 3 profiles in use for dawnguard. 1 vamp that I have had at lvl 35 just for the dlc, a paladin at lvl 35 just for dawnguard, and I just made a new dual wielding dawnguard person... Just to get an experience of everything at a low level and eventually rise. I love them all, so...