The Predator is the most basic Space Marine tank. It overall dropped in price in the latest codex, and has respectable armor and a decent range of weapons. It comes base with a turret-mounted autocannon, which you can upgrade to a twin-linked lascannon. For sponsons, it can take either heavy bolters or lascannons. This means that you can equip it for either anti-infantry or anti-armor.
The anti-infantry load-out is pretty straightforward, with an autocannon and heavy bolter sponsons. The anti-armor configuration can take either the autocannon or twin-linked lascannon for the turret along with lascannon sponsons. In both cases, the Predator provides solid firepower for the points. However, it has very stiff competition from other Heavy Support slots. The anti-infantry Predator really can’t compete with a Thunderfire Cannon. The anti-armor Predator is slightly less points efficient than a Devastator squad, but it is tougher against most of the firepower on the table and more mobile. If you want a Predator to do some damage, I suggest going all lascannons.
The Predator only really benefits from Iron Hands Chapter Tactics, but it is a significant benefit. It’s worth noting that the Imperial Fist Chapter Tactics destroy the balance between Predators and Devastators; giving Devastators Chapter Tactics makes them far superior, so don’t expect to see Predators in an Imperial Fists army.
The Whirlwind is the original Space Marine artillery platform. It’s basically a Rhino that mounts a large blast, Barrage heavy bolter or bolter with Ignore Cover. The Whirlwind is extremely cheap, costing you just under the points of two Rhinos.
Really, there is nothing wrong with the Whirlwind. Its main issue is that it’s totally outclassed by the Thunderfire Cannon (I’m getting tired of typing that). The only time that the Whirlwind comes out on top is when firing at 4+ save infantry in the open. If you catch Dire Avengers in the open, they will disappear. However, they probably wouldn’t survive all of the wounds caused by a Thunderfire, even getting their armor saves.
The Vindicator has the same chassis as the Predator, but only mounts a single weapon. However, that weapon is a demolisher cannon, which is one of the strongest weapons in the game. It also has the option to take a siege shield, which allows it to automatically pass Dangerous Terrain tests.
The demolisher cannon is both a blessing and a curse for the Vindicator. It allows it to threaten any target it fires at. However, it makes the Vindicator a priority target for the enemy. Its short range means two things. First, the enemy can concentrate fire on it early in the game to destroy it before it can fire. Second, it will have to advance to fire, likely exposing its weak side armor to enemy fire.
These weaknesses lead to two methods of playing the Vindicator. First, it can be your distraction unit. Take a single Vindicator and play it very aggressively, and it will attract all of your enemy’s anti-tank firepower. This is particularly useful if you are taking an army with lots of Rhinos, as it will allow you to get your squads into position. The second tactic is to make the Vindicators the centerpiece of your assault. Take as many as you can and use your Rhinos and marines to screen and protect them. This isn’t a terribly well-rounded army, but it can overwhelm opponents that can’t deal with heavy armor or rely on heavy infantry.
The Hunter is one of the new Space Marine tanks in this codex. It has extremely unorthodox AV 12 on the front and sides and carries the skyspear missile launcher. The skyspear fires a single S7 AP2 Armorbane, Skyfire shot, which is very likely to damage any flier that it hits. If it misses, the missile continues to seek its target and has the chance to hit its target on its rear armor in a later turn; it can shake this lock by moving off the table or into close-combat.
The Hunter provides cheap anti-air that is quite capable of damaging heavier fliers like Stormravens. It also has the ability to force your opponent to put his flier back into reserve if they don’t want to chance taking a strong hit to rear armor. Overall, it is a very cheap way to add reliable anti-air firepower to your army if you have open Heavy Support slots.
The Stalker is the counterpart to the Hunter. It has the same armor, but pays a few extra points to upgrade the skyspear missile launcher for an Icarus stormcannon array. This is essentially a quadgun, but it can choose to engage two targets. If it does, it still fires 4 shots at each, but they are no longer Twin-linked and are resolved at BS 2.
While the Hunter specializes in damaging heavier fliers, the Stalker is designed to destroy light fliers. In general, I wouldn’t split shots just because they become so much less accurate. Concentrate your fire and bring down a single target at a time.
In general, I think the Stalker is a better fit in most armies than the Hunter, simply because I see a lot more light fliers than heavy fliers on the table. In both cases, you have to decide if you want to take dedicated anti-air for a relatively cheap cost or take fliers of your own. Your own fliers will shoot down enemy fliers as well as targeting other enemy units, but they will cost more. I tend to go with fliers of my own, but that’s mostly because I’m using my Heavy Support slots for other units. It’s perfectly viable to take a couple Hunters or Stalkers and point the points you save into your ground forces.