Webpack
One of the most established and mature bundlers available today is webpack.
The following repository demonstrates the use of Webpack 4 along with Babel to use JavaScript ES6 with XLTS for AngularJS:
https://github.com/xlts-dev/angularjs-webpack-babel
Webpack can also be used with TypeScript.
Angular CLI
The following repository demonstrates the use of the Angular CLI with a hybrid TypeScript app that combines XLTS for AngularJS+Angular, Angular Material+AngularJS Material, and the Angular CDK:
https://github.com/xlts-dev/angularjs-angular-hybrid-angular-cli
Other bundlers
A number of new bundlers have started to emerge in the last few years. One of those that has been getting a lot of attention is Vite. The following repository demonstrates the use of Vite along with AngularJS Material and XLTS for AngularJS:
https://github.com/xlts-dev/angularjs-material-vite