Hmmm.
Bjj or Judo I'd say.
Honestly though, you can't go wrong with bjj, judo, or sambo.
BJJ = emphasis on groundwork, some takedown stuff.
Judo = emphasis on throws and takedowns with groundwork that has armbars and chokes.
Sambo = emphasis on throws with groundwork that has armbars and leg locks.
Which ever direction you go, if you stick with it, will serve you well. It really doesn't matter which style, it's about dedicating yourself to the one you chose. IMO.