When the bow tie was first made, there were no mass production machines that were capable of creating them (it should be said that I count the sewing machine as part of the handmade process as you must use your hands during use). Each tie was sewn individually, sometimes leading to bow ties that looked slightly different to each other. Nowadays there are machines that are capable of making thousands of ties an hour, without any need for human interaction.
If you are spending a large amount of money on a bow tie, then you will want one that is well made and will last for a long time. The higher the price of the bow tie, the more likely it will be handmade. Handmade bow ties in most cases will be marked handmade. Each tie is individually made by a person, which costs more, but leads to higher quality work. Companies that make handmade ties tend to have a lower output which allows them to put in place more quality control processes.
However for many people wearing a bow tie is something that happens very rarely, less than once a year. So there is little point in spending a large amount of money on something you will hardly ever use. But there are high quality mass produced bow ties out there. When dealing with machine made bow tie there are some materials that I would not recommend, as the process can be hard on some of the softer materials. Ties made from velvet, satin and wool should be avoided as they are tougher to puncture with a needle which puts more stress on the thread holes. I would stick with low grade silk and linen.
In terms of which one is better, I would always side with handmade, but this is because I regularly wear bow ties. I have some machine made ties at home that I love also, but only in the materials specified above. I would also agree that it largely comes down to psychology also, I feel more dressed up in a more expensive bow tie. It comes down to your own situation.