I chose wetwork, because I got to SR50 two days ago and didn't have all the specializations. I don't see myself using any of the abilities, save for maybe Pathfinder. So I'm just going to go with whatever and choose the least stupid sounding name as my last one.
For those who don't know, when you hit SR130, you can't change your specialization title. So if you have Wetwork for last, on your player card it will always say "Wetwork" underneath.