350 GSM holds a light product and a mailer. Kraft costs a little more and reads as paper rather than coated print. Soft-touch lamination changes the hand-feel more than the color.
If the product is heavy, or the box has to lock without tape, do not force it into a standard size. Choose custom dimensions in the configurator. That sends a quote instead of a checkout.
Print on the front panel first. The other faces can follow once the mark, the legal line, and the barcode have a home.