Today I would like to go over the "new" Tau HQ choices, but I will be going over them a little differently than most. For each HQ I will look at them in terms of using them in a Primary Detachment, followed by their use as an Allied Detachment. I use the word "new" as the majority of the HQ's are still the same, just with different options.
Primary Detachment: First things first, guy is a beast and just gives so many options. No Scatter on Deep strikes, AP2 Power Weapon with Armorbane, 3+, 4++ and best of all is the ability to take up to 7 bodyguards. If you're a deathstar type builder, it doesn't get much better than this. Add 7 suits with him (which all have Sworn Protector and means they suits automatically pass Look out Sir Rolls) all with fusion blasters or Plasma rifles, and you're going to destroy almost anything you land near. Solid Choice overall, and I expect to see him as the most chosen HQ for obvious reasons.
Allied Detachment: Farsight is the most expensive HQ in the codex, and he is amazing, in my opinion, its too many points to spend on an Allied HQ in order to make him work the way I would want. I could see him running with IG as a backfield threat. Personally I would rather run someone cheaper on points because my main objective is to cram in 3 broadsides and a Riptide, and I still have to have a unit of troops as well.
Primary Detachment: Second most expensive HQ in the Codex but still just as viable in my opinion. I believe that her greatest strength is the ability to grant her entire unit stealth and shrouded. Jump a unit of her and some suits, from ruin to ruin and exploit the cover save. You could technically attach her to a riptide as well (yes it is currently possible, look it up) and plop him in a ruin.
Allied Detachment: Depending on what you are running the Tau with, I could see her being very viable. The ability to outflank her and a unit of suits could be game changing, but again, would still be expensive in terms of point cost.
Primary Detachment: I'm still torn on him. I love the abilities he provides, in being able to use all the Ethereal abilities twice per turn and allow others to use his Leadership value for tests which is also rerollable against his LD which is 10. This means that ANYTHING within 12" of him will never fall back. Ever. He also has a pretty nice ability that will allow your entire army to get up after they have gone to ground, and move/shoot/act normally. His Paradox of Duality is also interesting in that he has a higher chance to make saves against lower AP Weapons, and autosaves against AP1, which I think will catch a lot of people off guard. In the end, If you get into CC with him, it wont matter, and he will get squashed like a bug with WS1.
Allied Detachment: Seeing as his abilities are geared toward protecting a larger force, I really don't see him being a solid choice in a allied detachment.
Primary Detachment: Very Melee oriented choice. I like the 4++ and his blademaster ability, while still being able to use all ethereal powers, but other than that, I don't see him being used a lot. There are too many better options unless you are building for Fluff.
Allied Detachment: If he has infiltrate or scout, I could see him being used a lot more. If you're running him, your running him with Kroot, and no one wants that. At least he makes them stubborn.
Primary Detachment: While I don't think he will be a great Primary HQ choice, I think he will be a very solid Secondary HQ choice at higher levels, especially for the points. Attach him to a unit of pathfinders and outflank into some area terrain or ruins. The unit then marker lights whatever it is that you want the rest of your force to be concentrating on, and then use his Structural analyzer to lower the Toughness of the unit you shoot at, meaning that you will be wounding most Xenos on 2's and Power Armor on 3's. Add the ability of him as his entire team to consolidate D6 after firing overwatch and you can keep them alive even longer.
Allied Detachment: Due to his low point cost and outflank ability, I consider him one of the top Allied HQ choices. As stated above, I would attach him to a unit of pathfinders, and out flank to marker light for my broadsides and rip tide.
Primary Detachment: The point cost is amazing, allowing you to squeeze in more and more units and shots. If your looking to run gunline, and just build a wall to move forward each turn, this is your guy. All ethereal powers to keep your stuff form retreating, Feel No Pain, etc...he's just full on support. Think Librarian. Except for one thing....he doesn't have a save of any kind at all...unless you give him a shield drone or attach him to much larger unit, then cram that unit in a devil fish, etc...personally I need a more resilient HQ as not to give up quick warlord points.
Allied Detachment: He's only 50 points which is a steal. Put him with a unit of firewarriors in a bastion, and just load up on Broadsides and a riptide.
Primary Detachment: Similar to Darkstridder. Great Secondary HQ choice in my opinion. The ability to give his entire unit an extra shot is better than you think. Attach him to a unit of 12 firewarriors with pulse rifles, and thats 24 S5 shots at range 30", if they get within 15" it jumps to 36.
Allied Detachment: As of this post, this is my current #1 HQ to use for an allied detachment. I currently run him with 1 shield drone, attached to a unit of 12 firewarriors with pusle rifles, behind an Aegis defense line with a Quad Gun. The Fireblade is BS5 and has split fire, which means that he can shoot at a unit different from the firewarriors. This is where he really shines in my opinion. He buffs the firewarriors for more shots, but since he is on the quad gun, He can shoot at flyers when they come in, then during the shooting phase, he can use his marker light to light targets for the broadsides or riptide. For the points, and ability he adds, currently I think he is the best option.
Primary Detachment: If you're looking for versatility, this is your guy. You can literally build him anyway you can think of, even melee, which I wouldn't advise. He can take almost any option in the book except ethereal powers, and he can take up to 2 bodyguards to keep him alive even longer. The commander is always an option.
Allied Detachment: While costing a little more points, he has sustainability. You can give him a shield generator for the 4++ and literally gear him for any roll needed. Personally I like to build him with an Iridium suit, Drone Controller, Fusion Blaster, Missile pods and 2 Gun Drones. Add in 2 bodyguards with Twin linked fusion blasters and Missile pods and 2 Gun Drones, and the unit of 3 can do almost anything you need them too over the course of the battle.
Well there you have it, it's only been 5 days so far, but these are my initial first impressions.
Questions or other Ideas, let us know!