Speaking as a metafandom compiler: I generally link to whichever version I see, unless there are crosslinks, in which case I link to whichever has more comments (or comments enabled). This means that if I see it on my dw flist/network, I link there, unless the dw version has a crosslink to enable me to check out the lj version. It's too much effort to figure out if someone also has an lj, and go find that post, if there is no explicit crosslink.

I don't know what the other compilers do - I'm speaking just for myself.