Welcome to the forums, cr78!
Go for the Caly3! The PE VG-10/G-10 variant was my first-ever
and, come to think of it, began my affinity for high-end cutlery. It is absolutely wonderful. I even carried it a few times in my old job as a teacher (when I really needed it and the kids weren't there), and it was almost completely unobtrusive with shirt/tie/slacks professional attire. Pocket space was not an issue. The only thing that concerned me was that the G-10 might start wearing out the pockets in my dress trousers, but I'd smoothed the G-10 in the area where the clip meets the handle with some sandpaper and nothing came of it. Maybe the CF variant is better in this regard; all I know is that I'm happy as a clam with my G-10 variant.
Now as a student, I EDC a Lava with the same attire. It sticks out like a sore thumb with its polished metal clip, but it's legal to carry in my neck of the woods. I love the Lava, but I wish I could carry the Caly3 legally, as it's far more discreet and its more acute tip is much better at opening envelopes. Plus you get a much longer blade for the same weight (stainless versus G-10 handles), which is helpful for food prep on the go.
I can't comment on the Delica and Rookie, as I don't have them, but I doubt you'd be disappointed with the Caly3.
Good luck with the decision!