The minimum quality is the chromolybden steel. Handlebars must resist in fall but to don't break.
The good compromise is aluminum 7000 serie. They have received a heat treatment that allows them to bend and regain their shape.
The leader in dirt bike handlebar is Neken a french factory in our city Angers !
The Renthal Twin Wall with its two layers seemed to be able to provide even greater security. Unforntnaly the rider prefer the comfort from the Neken and it seem it will stay also the most stronger !
The brand is not the most important for the quality. What is important is the material used. A lot of brands use the advertisement to be famous and use a low alumium 2000 series that is just good, no more !