There is no official rank. All servers are humbly serving Christ through preparation of the mass, and therefore, the motivation to serve the Altar should not be for rank or title. The first shall be last comes to mind here (Matthew 20:16).
For making altar serving simpler in terms of who does want, my parish growing up had ‘regular servers’ and ‘senior servers’ and the senior server made sure everything was set up, the Eucharistic ministers didn’t forget anything when they set up, and they are the crucifer or if used, the thurifer. My parish made this distinction physically known which I didn’t care for since it shows outward rank which has no need. But ‘regular servers’ had a hood on their alb and ‘senior servers’ had no hood on their alb.
This led to servers caring more about whether or not they wore a hood than actually serving Christ through the Eucharist. So if its for an organizational purpose I get it, but it takes away from what is actually happening in mass if a full hierarchy is established. After all, altar servers are not an ordained role or anything so all these ranks are purely made up by the parish priest. My church actually had an ‘installment’ mass for new servers with a set of prayers that required the response ‘I do’. Then when you graduated to go to college there was a ‘devestment’ mass, very odd and really just for show.