Broadsides are the big guns of the Tau army, carrying a Twin-linked Railgun.  No matter what size the army, it should have at least one Broadside.  They suffer from not being very maneuverable, but their accuracy, strength, and resiliency more than makes up for it.

Full teams of 3 are best.  As the Smart Missile System is free, it is the best secondary weapon -- the Plasma Rifles cost 10 more points, but if you aren't firing the Railguns, you are wasting your Broadsides.  Broadsides need to be placed with excellent fields of fire so that they do not have to move during the game.

For the support system, give all suits but one Target Lock so that you squad may split its fire if necessary.  The last suit should take a Drone Controller with a pair of Drones to divide up the hits.

Some people like to take the Multi-tracker for their support system, yet I find that this weapon will rarely fire.  The 72" range of the Railgun means that the Broadsides can (and should) be placed far from the enemy.  The 24" SMS is usually not in range, so I find the Target Locks a more useful choice here.

Placing the Ethereal with a Broadside team will negate the need to bond the team, as they will become Fearless.  It also is a way of adding more Drones to the squad to soak hits.

Hammerhead Gunships are one of the best Heavy Support choices in the game, combining mobility with powerful weaponry.  The biggest decision to make is to decide what weapons to take on your Hammerhead.

The easier choice is the Secondary Weapon.  As your skimmer should, if at all possible, move more than 6" every turn (in order for all hits to count as Glancing), you will only be firing one weapon each turn.  In most cases, this should be whatever primary turret armament you have, so your secondary weapon should be the cheapest option available: Burst Cannon.  Not only is it cheaper, but as weapons start to get blown off your tank, this gives the Hammerhead 3 weapons instead of 2 to lose before being rendered weapon-less.

The main gun depends upon your opponent.  In tournament-style play, when you do not know what you will face, the Railgun is a must, as it is more versatile.  The solid shot can threaten heavy armor, while the submunition round can really decimate large bodies of light infantry.

The Hammerhead, however, is the only way to take an Ion Cannon in the Tau army.  Really, the Ion Cannon should only be taken against Power-Armored opponents; anything with a 3+ save.  The Railgun's submunition round cannot penetrate marine armor, and statistically, the Ion Cannon will fare better over a 6-turn game than the Railgun against Marines or similarly armored armies.

Always equip your Hammerhead with Decoy Launchers to keep them in the game longer.  A Multi-tracker is another required piece of wargear for this tank, as you will always want to move over 6", and it will let you still fire a weapon.  If you know you are fighting at night, then the Blacksun Filter's extended range will confound your opponents.

  It is not so much the cost of Kroot Oxen that make them a poor choice so much as it is the fact that taking them uses up a Heavy Support slot on the Force Organization Chart; a slot that could be better used to field Broadsides or Hammerheads.

If they were simply an "add-on" to a Kroot Carnivore squad, in the manner of heavy weapon troopers in other lists, they would be an excellent choice -- Very menacing in close combat with a high Strength, Toughness, and 3 Wounds and Attacks, plus a S7 ranged attack -- it would be silly NOT to take them.

Taking up a valuable Heavy Support slot, however, renders them useless.  Other problems are the awkward Kroot Gun, which may fire once at 48" if standing still, but if the Kroot move at all, its range is reduced to 12", as well as only counting as having a T3 for instant-kill purposes.

The Ox is a great model, but unfortunately must be left on the shelf in favor of Broadsides and Hammerheads.  Only if you have the slot open, and are down to a few leftover points should it even be considered.