#Java 8, Butter

Spreads itself as evenly possible. Smothers a town if the town is sufficiently small.

import java.util.ArrayList;
import java.util.List;

public class Butter {

    int round;
    int playerID;
    int thisTownID;

    List<Town> towns;
    List<Town> myTowns;
    List<Town> otherTowns;

    Town thisTown;

    public static void main(String[] args){
        if (args.length == 0){
            System.out.println("34 34 34");
            return;
        }
        new Butter().spread(args[0].split(";"));
    }

    private void spread(String[] args) {
        round = Integer.parseInt(args[0]);
        playerID = Integer.parseInt(args[1]);
        thisTownID = Integer.parseInt(args[2]);
        towns = new ArrayList<>();
        myTowns = new ArrayList<>();
        otherTowns = new ArrayList<>();


        for (int i = 3; i < args.length; i++){
            towns.add(new Town(args[i]));
        }

        for (Town town : towns){
            if (town.isMine()){
                myTowns.add(town);
                if (town.isThisTown()){
                    thisTown = town;
                }
            } else {
                otherTowns.add(town);
            }
        }

        Town mySmallestTown = myTowns.stream().min((a, b) -> a.getFreeKnights() - b.getFreeKnights()).get();

        Town smallestEnemyTown = otherTowns.stream().min((a,b) -> a.knights - b.knights).get();

        if ((thisTown.getFreeKnights() - mySmallestTown.getFreeKnights())/2 > 0) {
            System.out.println("S " + mySmallestTown.getId() + " " + (thisTown.getFreeKnights() - mySmallestTown.getFreeKnights()) / 2);
        } else if (thisTown.getFreeKnights() / 2 > smallestEnemyTown.numberOfKnightsToConquer()){
            System.out.println("A " + smallestEnemyTown.getId() + " " + smallestEnemyTown.numberOfKnightsToConquer());
        } else {
            System.out.println("W");
        }
    }


    private class Town {
        private final int ownerId;
        private final int id;
        private final int knights;
        private final int lowborns;

        private Town(String string){
            String[] args = string.split("_");
            ownerId = Integer.parseInt(args[0]);
            id = Integer.parseInt(args[1]);
            knights = Integer.parseInt(args[2]);
            lowborns = Integer.parseInt(args[3]);
        }

        private int getId() {
            return id;
        }

        private int getOwner() {
            return ownerId;
        }

        private int knightCount() {
            return knights;
        }

        private int lowbornCount() {
            return lowborns;
        }

        private boolean isMine(){
            return ownerId == playerID;
        }

        private boolean isThisTown(){
            return id == thisTownID;
        }

        private int getFreeKnights() {
            return knights - lowborns / 2 - 1;
        }

        private int numberOfKnightsToConquer(){
            return ((knights * 6) / 5) + (lowborns / 2) + 1;
        }

    }
}

Compile: javac Butter.java

Run: java Butter