If you want a ranked voting system, Condorcet method - Wikipedia is probably a better approach than Instant-runoff voting - Wikipedia (aka as RCV or IRV or Hare).
It shows similar (good) properties to our current Approval voting - Wikipedia (see Ka-Ping Yee’s resources posted by @larry), while allowing voters to not only approve candidates, but also provide their own ranking, if they choose to do so.
We’re using this for the board elections of the EuroPython Society via the anonymous Condorcet Internet Voting Service.
The only problem we faced was ties on the last ranked position. The Schulze method we used for completion produced such a result in our last election (this is rather rare to happen).
Since you can’t have more candidates elected than there are positions available on the board, you then have to come up with some sort of resolution. This method should be predefined to not cause issues.
The above system outputs the results under multiple completion systems, so a possible solution is to define a predefined ordered list of completion methods to then turn to in case of a tie.
FWIW, I don’t have strong opinions either way. Both (non-ranked) approval voting and (ranked) Condorcet voting are fine, IMO. I don’t know anything about star voting, so can’t comment. RCV can result in rather serious issues (see e.g. the Wikipedia article or the Ka-Ping Yee resources), though, so I wouldn’t be in favor of that particular method.