You will get more attention to detail with a good American vendor,
Bleached single knots in the hairline which makes it look so much more realistic. You will also get custom density which helps keep the unit from looking wiggy.
You can also get the custom cut and color that was mentioned by an AV. An AV will also help you select the best type of hair for your look in terms of care and matching your own hair if you choose to do that. An AV will save you time researching on BHM.
There is benefits in going with an AV. I go with the Chinese because I'm cheap...