Most of the spoke makers do not actually make their own nipples. Nipple manufacture process and machinery is VERY different from spoke making, so most prefer to have them made by folks best equipped to do so.

In any case there's not a meaningful quality difference brand to brand. Instead, focus on the individual characteristics, like shape of the head, quality of the flats, and (most important) length of thread.

Spokes generally have 10mm of thread length, so I look for nipples with only 7-8mm of thread. That allows me to err to the long side with 2mm+ room for overrun. Confirm this by threading a spoke and seeing how far you can go beyond the head before bottoming. As a rule it's all a matter of preference, but if you're spokes are already on the long side, you MUST buy nipples that allow overrun.