There have been quite a few great suggestions & much of it really depends on how much you want to spend & what's comfortable to you.
So far, I really like BM's Activator. I had the S30V version (With twill & grey G-10 scales), but currently have a D2 version (With Winewood scales). At 5.5" OAL & a blade of 2 1/8", it's a comfortable small knife & I have very large hands.
Although I haven't handled them, I really like "MykelMorris's" designs (& prices, for that matter). Most of his FBs are made out of files (Usually at 57-59+ RC). I know he's also done frame-lock folders with 440C at 58-60 RC & I believe he's willing to use other SS blades on his FBs, instead of files, although I think he prefers to use them. Plus, I think they cost less, too.
The Bark Rivers are nice, but I just didn't find them comfortable, but that's just me. The Blind Horse Knives aren't bad either, but certain models aren't made of that great of steel, while others are & their price shows it. Of course, it's usually: "You get what you pay for."
Of course, the big names custom FBs are great, too (Krien, May, etc.).
Good luck with whatever you get.