it's an interesting question.
I bought some MAC samples (authentic of course): You're right about MAC ones have something in them to make the textures light and fluffy and 'magnetic' like (in a way I couldn't really describe it)
I haven't bought from TKB or CS; however I've bought from a lot mineral companies that happened to be RESELLERS from TKB or CS in that case. (same colors, textures, etc; after they bought the micas and slap their labels on them) Anyway, TKB and CS sell mostly just micas (okay, some with titanium dioxide, etc, but they do NOT have a base to stick them to your eyes; some micas have larger particles, so..) That's why it is a good reason to find a good mineral company that actually makes their eyeshadows, so you don't get repeat dupes or dislike how they don't stick well on your lids.
Comparison: I bought from Glamour doll eye's strawberry shortcake which is equivalent to TKB's strawberry in POP! micas. And the texture is smooth. Is the color unique? No, it's repacked TKB mica at a higher price.
I've had few greens from a company who make their colors and compare them to the greens I have from MAC: teal, spiritualize, some greens. MAC ones tend to have fluffy powder getting somewhere.... I can do a swatch for you if you like... Just reply to this thread.