My favorite thigh highs EVER were made by Hanes--they came in an extraordinarily natural-on-me color called "nude", had a pretty lace top, lasted forever, felt great, and you could order them in medium, which would fit up to 6ft (not this A/B and C/D sizing).  These are definitely not as good, but I've been trying out different brands and styles like crazy, and so far the closest I've found to my old holy grail thigh highs.

On colors: I've ordered these in Jet, Barely There, Travel Buff, and Little Color.  Jet is a standard sheer black.  Barely There looks god-awful on me--far too dark/orangey for my pale skin and reminiscent of your granny's knee-highs.  (Obviously these might look beautiful on someone with darker skin; they just suck on me.)  But then Travel Buff is unnaturally light, even on someone as fair as I am.  It's not light enough to look white, but not dark enough to look natural, so it just ends up looking a bit unhealthy.  Little Color is currently my go-to natural color, although the ideal shade for me would be just a little lighter than this.

On sizes: I've ordered these in both size A/B and C/D, and I can wear both, but neither is as perfect as the old medium.  The A/B fits nicely around, but doesn't come as high up on the thigh as I'd like.  I'm 5'11 and it only hits about halfway up on me.  I like them to come up higher because they feel more secure when they fit around the larger part of my thigh, plus you can wear them with shorter dresses/skirts, and they just look sexier, in my opinion.  So I started ordering C/D for the extra length.  The length on the C/D size is actually perfect, but I've noticed they tend to roll down a bit.  Not enough to actually fall down or anything--it's just the very top that tends to fold over.  I'm guessing this is due to their being a bit too big around, as the A/B size doesn't do this for me.  (Bring back Medium!)

These feel very nice--silky, not scratchy, and the lace top is much prettier than the non-lace kind.  The stay-up band is also nice and wide, which for me has been the secret to being able to comfortably keep them up all day.  Unfortunately these are significantly less durable than the old kind--some pairs have lasted fine, but on others my toe has broken through on a first wear.  (But as others have pointed out, thigh highs are great because you can still use the good half of a pair when you get a snag.)

Overall I'd recommend these.  I'll keep looking for something better, but as I said, I've tried a lot and thus far these are the best I can find, at least in this price range.