As of now the JQL operators <, >, <= and >= are available for only limited fields like for date/time field, issue hierarchy level, priority, and version field.

It would be great to have this operator for other fields like select list.

Note:

• From this public documentation,] some operators are not supported in certain field types;
  

Suggestions:
It would be great to have a wide array of operators supported in other field types. 

Workaround:

• Use of third-party plugin such as Scriptrunner