Ranks can be found using /res. Allowing custom premade titles would give incentive to donate or participate in whatever means needed to get them. These could be incredibly rare, valuable, and a reason to play. Helping player retention, This would require a command that pulls up a gui (similar to like /effect) the would allow you to pick what title you want visible. Edit: For staff, the staff rank tag would have to remain visible. This is an issue that can easily be worked out if the suggestion is accepted, since nothing is ever implemented immediately.