Another "only one" thread!
Normally I'd pass on this type of topic but I can answer the question without much thought.
My one folder....drum roll....Victorinox Pioneer.
I've owned hundreds of knives of all types and the knife I use more often than any other and that I have been using for over 25 years is the Pioneer or Soldier. They are the same except the Pioneer has a hole for a anyard. I have a few Farmer models but I've never needed the saw so I'm more inclined to go without the saw. The awl is my favorite blade. I carry either the Pioneer or Soldier everyday. Jeans or tux, it's in my front right pocket.
Victorinox alox Soldier/Pioneer.
I like my Pioneer (and really like my Alox Solo!) but the main blade lockup has always felt a bit "squishy". All the other stuff snaps nicely. Is this typical? The Solo has a nice lockup but it has nothing else on that spring.