Folder faves change every couple years for me if not sooner for various reasons having to do with a serious addiction

but I do have steady faves.
My fave user is a small single blade lignum Scagel Repro that my friend Dirk (Oupa) built using a Northwoods original two blade folder to make two separate folders from. He did this one and a few others for me out of some original lignum wood found in the attic of what was once Bill Scagel's shop (documented) and those are probably some that will remain a fave for me. The small one I will never part with and in fact its in my pocket today and sees lots of carry time.
Custom locking pocket clip style folders? My Bill Vining DPOJ and my Gene Baskett Tactical folder are two of my current favorites for customs and ironically both are liner locks which I normally shy away from. But I also have a couple small ones in the form of my Peter Bald small lockback wharny and my Dick Atkinson small frame lock wharny that I adore also.
Productions are hard for me to allow myself to get really attached to due to the nature of my work and the fact that I often times have a different one in my pocket from one day to the next so my steady users are usually the one I have on or in my left pocket. There is a little known thing about me actually. Its a funny thing about me I guess and its that no matter which modern locking pocket clip equipped folder I may be carrying on my right pocket from day to day I always have one of just a few favored slip joints I own in my left pocket. Always! When it comes to my roots I've never really been able to fully shake the habit of a slippie in my left pocket riding deep. So, with that said, my favorite production slippie is that little Scagel and right behind it is my 2001 Marbles Tear Drop Buffalo easy opener two blade. For years though during my Air Force days I carried a slimline Buck Esquire until losing it rock climbing. Still have one of those originals from when they were still made with 440C but its a collector piece and not a user. They call it the Squire now.
I have a fairly large collection of knives and my 'collector faves' are different than my user faves. I think I like the old Gerber Slimline PK knives and the Gerber original small Sportsman lockback folders the most but I have others also that I like a lot.
On fixed. I really don't have too many fixed blades at all. What I have I use. My favorite custom fixed is a blue jean 'mycarta' one in mirror polished D2 by our own Lloyd "Butch" Harner (Butcher_Block here on blade forums) which has a super nice gray colored kydex sheath he did for it also. This knife actually knocked a Dozier Personal out of first place for me.
My fave production big fixed is the Camp Tramp. Small fixed would either my Mora or a little fixed done for me by Dirk (Oupa) in a trade deal that I made a sheath for. It reminds me of a very old Case I used to own as a boy and I really like how he did it. I'll try to find a scan of it here in a bit.
STR