That would be none.
What would the point be? I have my home here on LJ where the vast majority of my dear friends are. It offers me pretty much everything I want and I'm quite content with it.
I have a back-up account on DW should anything permanent happen to LJ. I have a Twitter account (which these days I mainly use for direct messages) Why would I want yet another blog/social networking place?
One is enough for me.
Also, I don't do 'new' and 'hype'. It took me long enough to get an LJ account (*waves to <lj user="caffyolay"*) after vowing I never would; ditto a Twitter account - which I barely use these day apart from DM'ing a couple of good friends. This probably makes me boring and staid and unadventurous and old-fashioned - all of which sums me up perfectly *g*