I haven't been on the Spyderco part of BF in a while now as I kind of fell out of the tactical thing for a bit of time. Starting to get back into it now though.
My recommendation would have to be the Endura. My first Spyderco was a regular Endura that was used really, really hard and in a very salty environment.
The knife just stood up to anything that I threw at it. Used it everyday, multiple times. The only flaw was that my Endura didn't have the full flat ground blade.
Why was this a problem? Because I could never get the knife as razor sharp as it was out of the box (no matter what technique or system I tried to sharpen it with).
The point, I would highly recommend the Endura.
But, if you can wait a little bit of time and save up the amount of cash that you would need, I would recommend the Para-Military or the Military even more.
Again though, you cannot go wrong with the Endura.