What is the best way to defend White Forest in Half-Life 2: Episode Two?
My favourite tactic consists in picking up a log with the Gravity Gun, and whack those hunters with them; and when there's no log in convenient proximity, I use the Revolver or Shotgun (but I prefer the Revolver, since it's more accurate) to kill them as fast as possible.
The advantage of using logs (or rocks), is that they are available in abundance and that they can kill a Hunter with a single shot, assuming the shot hits, which is why you'd want to get close and personal.
There are only few weapons that can kill Hunters in a single shot, and all of them have extremely limited ammo.
The advantage of the Revolver and Shotgun, is that they can kill a Hunter in about 2-3 shots, although in the case of the Shotgun it can require more than 3 shots due to the Shotgun's low accuracy and range.
Of course, this assumes that you can survive a close encounter with the Hunters, which you'll have to anyways, since they rarely leave the Striders' side and you'll have to be fairly close to the Strider, if you want to successfully land a Magnussen.
You may want to explore the neighbourhood first though, so you won't waste time finding the Striders as they appear.
P.S: You actually can kill the Striders without dealing with the Hunters first, but in order to do this, you'll need to be extremely fast, both when picking up the Magnussen and launching it, and when switching to the handgun and detonating the device.
This is also extremely useful (if not required) when going for the Neighborhood Watch Achievement/Trophy, as you usually have plenty of time to deal with the Hunters in between two Strider waves, yet barely enough to deal with them before the Strider destroys a building.
Remember that the car is itself a weapon. Hitting a Hunter at a moderate or higher speed will kill it instantly. My tactic was to use the car's on-board radar (plus the loudspeaker announcements) to locate and intercept the Striders and Hunters as soon as they appeared. This is critical to the strategy, so that the silo is not taking damage while you are dealing with the Hunters. On the initial intercept, largely ignore the Striders and focus on running over the Hunters. Once they are taken out, drive back to one of the Magnusson-dispensing huts closer to the silo before getting out of the car and going after the Striders.
This is harder than it sounds, and I went through a lot of death/reload cycles refining the timing and technique. The car, like all of the vehicles, can be a pain in the ass to steer with an Xbox controller. I imagine it would be easier on a PC. There's also a significant element of luck to it. You want to catch the Hunters on one of the more wide-open roadways, such as near the sawmill. They are pretty good at jumping sideways to avoid getting hit, so you have to be ready to make that last-second swerve. Sometimes you get lucky and are able to hit one then back over the other. Generally, though, you want to avoid having to back up whenever you're within their weapons range. You'll take less damage if you make a run at them, get past their range, and then turn or loop around for another run. Hunters won't follow you very far from the Strider they are escorting.
This tactic does require a willingness to take a good bit of damage. Some Hunters are particularly good at jumping out of the car's path, and the only time they'll remain still is when they've got those barbs stuck to you. If you drive out of range or run over the Hunter before the barbs explode, you will take less damage. Remember that the health kits at whichever hut you are away from will respawn after each autosave when you kill a Strider, so in the brief lull before new Striders appear on the radar you need to race to the other hut and resupply.
The vehicular assault tactic works pretty well against one or two Strider/Hunter teams at a time. For the final onslaught, you may be able to run down only one set of Hunters before needing to return and defend the silo. At that point, it helps to be aware of what the Hunters are paying attention to. You may be able to occasionally kill a Strider without first killing all its Hunter escorts if the Hunter is occupied with your squad members.
Oh, and create a manual save point every time you kill a Strider. That helps a lot.