I started by carrying a slipjoint when I was a Cub Scout and got my Totin' Chip, with my scout troop (419) in Baltimore. It was a little tiny MOP-handled pocketknife that had been my father's first knife when he was a boy.
From there, I "graduated" to SAK knockoffs and cheap Imperial-type barlows, the kind you'd get for a buck at the local Bait & Tackle store at the beach.
Once I was finally old enough to take my knife selection into my own hands, I got my folks to buy me a Gerber EZ-Out, and carried that thing for most of my teens. It went with me all over the state of MD, through many hiking and camping trips, and dutifully rose to many challenges during my years of volunteering at the local nature center.
At that same nature center, I was exposed to various other options. The head naturalist carried a Buck 112, and some of the others chose various one-handers, which provided my introduction to Spyderco and Benchmade. I remember lusting after a BM 710 for most of my high school years, but it was out of reach ($$$).
Toward the end of high school, I discovered balisongs, and I started with a Jaguar. Eventually, I saved enough money to pick up a BM42AS, which changed my whole experience.
In the following years, my knife tastes drifted away from the slipjoints and more toward the one-handers. I tried Spydercos, Benchmades, Emersons, et al.
Eventually, I grew to once again appreciate the craftsmanship behind a nice traditional knife, and fell in love with slipjoints all over again.
Now, I generally carry two knives at a time: a slipjoint and a one-hander (usually a balisong, but often another mid-range... Spydie, Emerson, Al Mar). I like both, for different reasons. In my line of work, sometimes it's handy to have a blade I can deploy, use, and stow all with one hand. But, I still prefer the laser-like slicing ability of a thin carbon steel blade. And, of course, I'm still a balisong fanatic, and I enjoy flipping and using high quality knives. My balisong collection includes Benchmades, a Roton, some FHMs, and a custom. I have a couple custom slipjoints, too, but usually can't afford to dabble in that realm too much.
As I've matured so far, I've come to realize that I need a blacktical-tactical knife less and less, so even my one-handed knives tend toward slim slicers, and away from thick folding prybars. If I need a really rugged knife, I'll use a fixed blade.
I think that this path is probably the one I'll stay on.