The three brushes in my sig are the ones I use regularly. None of them are perfect "all-'rounders": which one I use depends on the kind of painting I'm doing.
The HP-TH (same brush as the Kustom-TH) is the simplest to use, easiest to clean, and excels at large scale work. It also has the best atomization of the three, and is excellent with thicker paints or paints with large or irregular particle sizes. Downside is it's no good for detail. I use it for priming, base color blocking, and clear coating.
The side-feed SOTAR has the best ergonomics and the second-best atomization. I use it for when I have to do complicated stuff in a small area, as it comes closest by far to the feel of using a pen, pencil, or "hairy" brush. Downside is the fit and finish are not as nice as the Iwatas', so it's fussier to maintain. The "side-feed" distinction is VERY important: I also have a normal gravity-feed SOTAR, and the two are very different brushes both ergonomically and maintenance-wise. I never use the gravity feed one, as it has too much overlap with the easier to use and clean HP-CS, but the side feed one brings enough advantages to the table to make it distinctly better as a dedicated detail brush.
The Eclipse HP-CS is the closest to an all-'rounder of the three. If I had to pick one of the three to be my "desert island" brush, it would be this one. Better at mid-small stuff than the TH, and more easygoing to use and clean than the SOTAR. I use it for anything too complex for the TH, but not quite requiring/justifying the deftness of the SF SOTAR. Anything I can do with the SF SOTAR, I can also do with the CS, but the SF SOTAR requires less hand-eye concentration, and is faster/easier when switching colors. The CS is less strict when it comes to reduction though, and end-of-session cleaning is simpler.
There are many brushes I'm absolutely hungry to try, but I have no means to do so without buying them. There are no shops within hundreds of miles of me that carry any kind of selection or allow in-shop demoing, and airbrush classes are out of my range in both sign-up and travel costs. I'm just a hobby modelmaker, not a professional painter, so these are not expenses I can write off or that will pay for themselves. For me airbrushes are a specialty tool within my hobby, not a hobby unto themselves, so a large expensive collection of ABs is not practical or desirable for me. If I were to buy another brush at this point, It'd have to be a direct upgrade replacement for one or more of the above, not a lateral alternative.
I wouldn't call any of my brushes an "extension of my hand", exactly, but I'm comfortably set from a "needs" perspective, so unless I have the opportunity to try a given brush in person AND it really wows me, the only brushes I could see myself buying "cold" are a CM-SB (can't afford it, otherwise I would), or replacing the HP-CS with an SBS (not necessary, just "would be nice", so pretty low priority).