As has been said above, there is really no such thing as an "XLR" or a "TRS" cable. These are connectors. There is, however a big difference in the "type" of cable that can be used between these connectors, which may specifically apply in your situation. That is the use of "starquad" or "non-starquad" cable.
Starquad cable is a form of balanced cable which has two conductors for each signal path (+ve phase and -ve phase). These conductors are arranged at the corners of a square so that each identical conductor is opposite its pair and the opposite phase appears at the other two corners. A slight twist is introduced during manufacture. These cables are also well shielded with a ground braid connector.
This type of cable has been shown to exhibit superior coincident rejection of induced signal over standard three conductor cables so are particularly suited for use in environments where you may not have control over where the signal cable is being placed, i.e. next to lighting ballasts and other mains cable.
For a music festival such as the one you mention, you will need Neutrik XLR Connectors and lots of starquad. These days most long cable runs are done digitally but if you are still going analogue, then starquad is the way to go.