To me a good set of dice should be:
Readable - you should be able to discern the rolled values at a glance from across the table. This means a single opaque color, with contrasting numbers in large print.
Easily Discernible - you should be able to instantly identify the type of dice you need. This means that dice with similar shapes (such as D8/D10 or D12/D20 should be color coded)
Plentiful - you should always have enough dice of a specific type to cover any situation in a given game system So for example a D&D set should have a dozen or so D6 dice, a handful of D4’s at least two D20’s and etc.
I feel that a set like that provides an optimal gaming experience. Most high end, fancy dice sets you can buy online offer the exact opposite: you get one die of each type, they are all the same color, they’re often semi-transparent, and the numbers are frequently stylized as runes hurting readability.
I personally like opaque D&G dice. They are slightly smaller than cheesex, they have excellent readability and fit snugly in my dice tray.
Pick your own colors and build your own set from scratch.
Alternatively, get the Dice of Rolling set that is built for D&D:
It’s a great starter set that checks all the boxes mentioned above.
Sometimes you need non-standard dice for specific edge cases: