Tights have quietly sorted themselves out over the last few years. The deniers used to feel like a choice between surgical and see through, with nothing sensible in between, and the matte black pair that bagged at the knee by lunchtime was just something you put up with. Now the range of finishes is wider and the quality at the lower end has actually improved, which is a rare thing to say about any basic. It is a change for the better, even if it took a while.
The easiest shades to live with are the ones that do not try to match anything exactly. A true black in a soft, not shiny, forty denier goes under almost everything and never looks like it is trying to coordinate with your shoes. Nude works too, but only if you take the trouble to find one close to your own skin rather than the bottle tan shade every shop seems to default to, because a nude that misses looks more noticeable than bare legs would have. Deep brown has become a proper neutral in its own right, and it is far more forgiving with autumn colours than black, which can look a bit harsh against rust or mustard. If you are starting from nothing, buy a plain black pair in a mid denier first, something around forty, since it covers cold office mornings and a dinner out without being so thick it looks like legwear for hiking.
Once you have that, tights pair easily with the things already hanging up. A wool skirt, ankle boots and a black pair is about as low effort as getting dressed gets, and a dark tight under a dress in winter buys you another two months of wearing something you'd otherwise have put away in October. They sit well with knits, with loafers, with pretty much any hemline that sits above the knee when the weather turns properly cold. Where they struggle is heat and humidity, obviously, but also with very textured tights under anything equally busy, a patterned tight under a printed skirt just reads as too much happening below the waist. Sheer black under a sheer or lace dress can look like an accident rather than a decision, and a shiny opaque under a satin skirt will fight it for attention all evening.
If I were buying one pair to start, I would go for a matte black in a mid denier. It does not photograph oddly under flash, it survives sitting through a long meal without going baggy at the knee, and it never looks like it is trying too hard, which is exactly what you want from something under a skirt.