Paraffin, soy, coconut, beeswax and blends
Updated
The wax decides throw, appearance, burn time and most of the defects in the next section. It is the first choice and the hardest to change later.
Four bases and a lot of blends
Most commercial container wax is a blend, sold under a product number rather than a material name. The number is what matters: "soy wax" describes a category, and two soy container waxes behave differently enough to need separate testing.
Which means the useful discipline is to record the product number and supplier rather than the wax type, because that is the thing that reproduces.
Paraffin
The strongest scent throw, the smoothest surface, the most reliable behavior, and the cheapest.
It is petroleum-derived, which is the whole of its problem in this market: a large part of the handmade candle customer base has decided against it.
Technically it is the easy answer and commercially it is often not, and it is worth being honest with yourself about which of those is driving your choice.
Soy
The default in handmade candles. Natural-origin, renewable, and the marketing position most of this market occupies.
It also brings almost every appearance defect in the craft: frosting, wet spots, uneven tops, sinkholes. None of them affects performance and all of them generate complaints.
Scent throw is weaker than paraffin at the same load, which is why soy candles tend to be made at higher fragrance loads, which is its own problem.
Coconut and beeswax
Coconut blends have excellent throw and a smooth finish, and cost more. Usually blended rather than used alone.
Beeswax burns long and clean with its own honey smell, which fights any fragrance you add. It is really a product for unscented or lightly scented candles, and it is expensive.
Both are niche positions rather than defaults, and both are easier to price well because the customer already expects to pay more.