I also vote for the Pioneer. My first Victorinox was a Cadet. I loved what a thin and ultralight knife it was. Next, I bought a Farmer. I was surprised how much more robust the 93mm line was. You are probably already aware of this, but the 93mm line uses thicker tools and blade stock than the other models. I loved how solid the Farmer was, but it was just a little too thick for my tastes. I also came to realize that I didn't really use a saw much.
Next, I bought a Pioneer, and it was perfect for me. Thin, yet built like a tank.
Another cool thing about the Pioneer is that it is essentially the same knife the Swiss Army issued to its soldiers for nearly 50 years. The Pioneer was introduced in the late 50's. When the Swiss Military was looking to redesign their Soldier knife, they adopted the Pioneer design. The 1961 Alox Soldier was a Pioneer without a keyring and a couple of small cosmetic differences. The Soldier kept this design until 2008. This kind of gives the Pioneer a neat place in knife history in my opinion.