For the "In the near future, how can a recommendations source (like, you know, me) be of most use to you?" question, my "Other" answer is that I would keep reading your recs no matter where you went. :)

I myself have set up accounts at all the other sites but haven't really used any of them much. I think no matter what, I will continue using LJ in one form or another, because I bought myself a perm account a year or so back (ugh, before everything bad that has come after 6A took over started) so I will keep using up my allotted bandwidth until they pry it from my cold, dead fingers. But if I had to move somewhere else for fannish activities, I would.