SWE and ASCE, although I just let my ASCE membership lapse, because it happens over the holidays. I was very active in SWE until this year, I have been on the board pretty much my entire engineering career, and really, even before. I have held all positions in out local section. ASCE asked me this year if I would consider being on the board since i had completed my SWE obligation, but I had to take break this year.
I am a co-chair for a conference that our local ASCE/SAME sections put on every year, so that is some involvement I suppose.
My company will pay for one technical, one civic and one professional society membership. So I do ASCE as my professional and SWE as my civic (it's a stretch, but they don't question it. I have not picked a technical, as a lot of them the company is a member of.