I'm very much new to Pathfinder so my first thought was to create a 2-weapon Fighter 'cause that seemed cool at the time. Anyway, after consulting the weapons list I've narrowed it down to these murder machines.
-The Estoc, 2d4 18-20/x2
-The Falcata, 1d8 19-20/x3
For me it's pretty much a decision between critical range and critical damage, since both have very good overall critical modifiers.
I'm somewhat more inclined towards the Estoc because (As far as I know) either Keen or Improved Critical bumps it up to 15-20/x2, whilst with the Falcata it's bumped to 17-20/x3. Also, I've noticed that the feats that add critical effects could be very powerful with a high threat range.
However, since I'm essentially learning Pathfinder I don't have much experience with what's more viable. Any thoughts or pointers would be very much appreciated.