I voted for the Goliath too. I just love sitting there by the center tunnel and picking off unwelcomed guests as they come through... 😀
Anyway, I've assembled a few tips for first-time players, based on my experience:
Manta:
* Don't get to carried away with speed, it's hard to control at top airspeeds and you can end up against a cliff face with your back to an AVRIL-weilding opponent.
* To mow down foot soldiers like grass, hold the crouch button (default is "C" I'm told) as you fly towards them, otherwise you'll fly right over their heads.
* One hit with any of these is lethal: Tank shell, fully-charged Hellbender rear turret, AVRiL
Raptor:
* Flying it can be a little tricky if you've never played Descent, and even if you have. Forward/backward movement, slide and pitch/yaw should be obvious, but I see a lot of people having problems with altitude control. You use your jump button to climb, and the crouch button to descend.
* Tank shells are dumbfire and as such are trivial to dodge, but air-to-air and AVRIL missiles home in, and do so quite well. The best way to shake them is to fly right at them then slide out of the way at the last second.
* I think aiming is a little easier in first-person mode.
Hellbender:
* Like all land vehicles, you steer it with the strafe keys.
* Try to get two teammates to join you. With a full gunner compliment this thing is deadlier than the tank.
* Failing that, drive to wherever you expect the enemy to show up, then press "2" or "3" to switch to the turrets. (thanks HelloDeli!)
* To be of any use, the rear turret should be charged for at least a second. At full charge, it is the most devistating weapon in the game, save for the redeemer...
* The side turret has some significant destructive power of its own. Fire a string of energy blobs at a group of approaching opponents, then use the secondary fire to set off a chain reaction. This is also a good way to wear down a power node.
Scorpion:
* The main weapon fires a stream of energy that acts like a rope. If you hit an object, the free end(s) will swing around, grabbing anything they touch, then the "blobs" will explode. Some fun things to do with this weapon include: Tying an opponent to a vehicle, tying an opponent's flying vehicle to a tree then watching it slam into a cliff, tying two or more opponents together...
* Hold the secondary fire button to deploy the side blades. These will chop opposing foot soldiers in half and damage power nodes and enemy vehicles. If you run into something with them, they'll break off.
Goliath:
* The main gun rotates slowly. Try not to get too far ahead of it or you'll get picked off by a manta while you're waiting for it.
* It would be nice to have a gunner to operate the roof-mounted minigun. He can pick off enemies while you concentrate on blowing up a power node.
* It may have 800 hit points, but a flak gunner on foot can rip it open in seconds if you're not careful. If you can't run over him, hit "2" to switch to the machinegun and kill him that way.