None of them?
Usually the best way it is to buy from a nursery. You may have your own nursery and own orchard, but the first is usually more complex (and it may have more regulation), so it is not the good way to start. But if you go in this direction, you can plant the tree much denser (possibly where it is also easier to water, and to fertilize, and with good control of wild animals and or wind).
Then it depends on the species do you want. Many plants requires grafting. In this case, for the top part you need existing branches (and of the correct variety). According your climate, you may need a specific grafting method (freezing, dry weather, etc...).
For the rood part: this is maybe the more tricky part: you may need a different species (or just the correct variety). The choice depends on many parameters: the form of your orchard, but also on your local climate (wet/dry) and soil. The optimal root gives you much earlier and much more fruits. This may come from seeds or from branches, or from shot which come directly from bottom/underground. It depends on the species.
For some species, you do not need grafting, but then it is more tricky to have a variety with good production with your soil/climate (and a variety which you can sell easily the fruits... consumers are not a rational species). Seed usually takes a lot time before they produce good fruits.
And your question "fastest way" may give you the wrong way. You can force a tree to produce earlier a fruit, but usually you want a healthy plant, which will produce much more fruits, and for much more time. In fact, it is very recommended to remove all or most fruits on first years of production (on many species).
I'm sorry, this is not a good answer, it is difficult to answer a so generic question). You may need to ask a more focused question. I think you should start buying from a nursery good plants (and different varieties). check what it is the best for you, and then use their branches to expand your orchard. Or just buy an existing orchard (as starting point, to get on economic part: selling fruits, machinery, experience). There are so many abandoned orchards, and old people who likes if somebody will continue their orchard.