Well, since there's been a sale on WALB and an influx of newbies, I thought I'd share some good starter decks, as well as why I pick those units. These decks are made more with destruction in mind, but can do OK in conquest with a few tweaks.
First up is the NATO offering, Cat A USA
http://i.imgur.com/7kO7qSv.jpg
Logistics
M577 CPC - A decently priced command unit, no useless weapon to give it's position away and 2 front and side armour to help against near misses from artillery and bombs.
M35 Cargo - Bog standard cargo truck, hide it in forest behind where you want to resupply. It's cheap and small so can be snuck up to the front without too much risk.
CH-47C Super Chinook - Big flying mini-FOB. Use this for resupply points behind the front (like you long range radar AA or armour that can fall back out of the line). Unlike the trucks, this will be a prime target so keep it safe.
FOB - 16000 units of supply. Essential IMO, even if you don't use it, it's there for the rest of your team.
Infantry
Mountaineers, Hardened in Chinook - A good all round unit let down by crappy transport choices of either big expensive helicopter or weak slow truck. Chuck them in buildings and woods at chokepoints and let the Dragon II ATGM kill anything that isn't an MBT and whittle down actual tanks too.
Assault Engineers, Trained in Humvee - These guys wreck infantry with the FLASH launcher but suffer against armour. Use in forests and for town clearance.l The Humvee is weak but goes like a stabbed rat, which his helpful when you need these guys to go hunting for SF behind your lines.
Delta Force, Veteran in UH-60 Blackhawk - Speaking of SF, here's the American option. Some of the best anti-infantry SF in the game, as long as you don't run into flamers. Sneak around forest and hill to blow up enemy artillery and commands with the M72 LAW. Blackhawks are taken on grounds of speed, firepower and cool.
LAAD Stinger, Trained in M113A1 - A great MANPADS Unit, use these guys to add saturation AA fire to your positions and support infantry pushes through woods and hills. The M113 is there to keep them safe from stray bullets and arty rounds, not to get in a fight.
Riflemen, Trained in M113A1 Dragon - Your cannon fodder infantry, use for flank security, holding down words and towns and general stuff you need to throw rifles at but not break the bank in the process. The M16 makes them one of the better NATO infantry for fighting in close quarters (Other units tend to have Battle Rifles). These M113's come with a dragon ATGM on the roof, so use them for supporting the infantry or setting up short range ambushes on supply routes.
Rifleman, Veteran in M2A1 Bradley IFV - You take this for the Bradley. See above for the riflemen, although these guys are a little better due to veterancy. M2A1 comes with a Bushmaster AC (Awesome) and a TOW 2 ATGM (Even better) The TOW 2 can mess up high end Soviet tanks with ease and will pop lower end stuff (T-72 and weaker) in one hit. These form the backbone of this deck in defence and offence, just keep them well supplied with TOW missiles and you'll do well. The AC also wrecks light units and infantry, and can be used against tanks at knife fight range.
US Marines, Hardened in UH-1E Huey - 'Muhreens! These guys are your shock troops, support with Assault Engineers and use against dug in positions in towns and forest. The weapons are similar to rifleman but a little bit better and come with 15 men instead of 10. Marines get a good selection of transport, but I've picked the UH-1E to give air mobility, since these guys get used a a 'fire brigade' in my experience. Other choices are the excellent LAV-25 and AA7P-A1 ground vehicles.
Support
M109A6 Paladin, Veteran - Damn good barrage artillery and precise enough to hit point targets with recon. All that needs to be said really.
M163 PIVADS, Trained - Best gun based AA you get. Short ranged but will chew up anything that gets into it's range thanks to super OP vulcan cannon.
M727 I-HAWK, Trained - Your backbone Radar AA. Accurate and hard hitting, but supply intensive as they need to reload after 3 rounds. You want these behind your front lines and ideally near roads since the off-road speed is horrible. Spread them well and any plane attacking you will likely be hit by at least 1 missile.
M48A1 Chaparral, Trained - Super good Infra-Red missile AA, but needs reloading after 4 rounds. Those 4 rounds though... This outranges almost every helicopter based ATGM in the game, so use this against pesky Hinds and MI-28's that think they can snipe you. The only thing you don't outrange is the KA-50 who you tie with, and he only has 2 shots.
Tanks
M1A1 Abrams, Hardened - Best NATO all rounder heavy tank. Good balance of Armour, Speed and Firepower. This will attract a LOT of attention so support with Bradleys, PIVADS and Chaparrals. Support it well and this will do brilliantly, rush it solo and you'll loose it to cheap crap.
M1IP Abrams, Hardened, 2x Cards - This will be your workhorse tank. Same armour as the M1A1, less effective gun that will still do the job. Same applies as above, but you can be more cavalier with this one.
Recon
M3A1 Bradley CFV, Hardended - Re-read everythign I said about the M2A1. Now add Very Good optics and 3x the TOW ammo so resupply isn't an issue. Expensive but you really get what you pay for. Just keep it behind in the attack to spot enemies since it will be a prime target.
OH-58D Kiowa Warrior, Hardened - Speaking of Prime targets, here's a unit that might as well have bullseye painted on it. Exceptional optics, 4 Hellfire missiles and only 2 a card. Keep this behind your front line, ideally on a hill and spot all of the things. If your line gets ruptured, the Hellfires put an end to expensive armour to give you a chance to stabilize. Your opponent will want this dead
really badly, but surround it with AA and any enterprising fighter pilots sent after it will have a rude surprise waiting for them. If you're worried about the risk reward ratio, drop down for the cheaper and more numerous OH-58C Kiowa.
Rangers, Hardened, in UH-1H - Affordable recon infantry in a cheap Helo. Put in strategic locations and spot stuff. The Carl Gustav and good speed and stealth stats also makes them a good candidate for infiltration and accompanying Delta Force on sneaky missions.
Vehicle
M67A1 Zippo, Trained - Flame tank goodness, these are your best friends in towns and forests. The actual chassis is weak, but still tougher than the M113 based option. These will probably die a lot, but flames don't need accuracy so take at trained to maximise numbers.
Helo
AH-64 Apache, Hardened - The 8 Fire and Forget Hellfires are what you buy this for, the cannon and Hydras are window dressing. I prefer to use the cheaper Cobra series for general purpose ground support, bring this out to met its intended purpose of stopping armoured offensives dead in the water. Protip - Turn the hellfires off after firing each missile, or they'll spam two at each target, which is usually one more than needed
AH-1F Cobra, Hardened - A nice affordable general purpose Gunship, with a Cannon, Rockets and 8 I-TOW missiles. I like to have two of these as soon as possible, hotkeyed and used in a cycle so there's always at least one ready to go at any one time. Probably my favourite unit in any US deck.
Planes
F-15C Eagle, Rookie - Damn good ASF that tends to win most 1-on-1 engagements. You'll need to be more careful when going 2 on 1, but if you get the drop or engage over your own SAM sites, you should be good. Don;t waste this on helicopters, fast movers aren't the best against them, and tend to cost a hell of a lot more.
F-4S Phantom II, Trained- Fast movers with napalm bombs and Sidewinders for self-defence and opportunistic chopper hunting. The ECM on thse guys is shocking, so you might want to escort them with...
EA-6B Prowler, Trained - Exceptional ECM and 4X SEAD missiles. These home in on radar guided AA, which just happens to be the best ground based counter to jets. Dumb opponents will loose their AA by leaving the radars on, smart ones will turn them off and loose their AA grid, which is where the ground attack jets come in to say hi
Win-win!
F/A-18C Hornet, Trained - Best Maverick carrier in the game for well protected targets. Carries the same Fire & Forget hellfire as the A-10 but has Very Good ECM to keep it alive, as well as Vulcan and Sidewinders for self-defence. It's very expensive, to the point of almost not including it an a starter deck, but treat it well and you'll love it. This is your personal sniper rifle.
Other possible planes
US Airpower gives you a lot of toys to play with, here's some other good picks.
A-10 Thunderbolt II - It's an A-10. You play Arma and you want me to tell you what an A-10 does?!
F-111E/F Aardvark - Big fast thing with the choice of either HE and crap ECM or Cluster and Better ECM. Very nasty in Cat C spamdecks since you get two to a card.
F-14 Tomcat - Rather than taking the highway to the danger zone, this thing orbits in the backfield and chucks missiles across the map. Another Cat C nasty
A-4 Skyhawk series - Cheap rocket planes for infantry support and killing weak units.
A6-E TRAM - A great Prowler escort, since they use the same airframe and travel at the same speed. Lots of HE bombs on it too and good availability.
EF-111A Raven - SEAD jet like the Prowler. This takes a better missile but only has 2 missiles and coems at 1 per card. Mostly a matter of taste over which you take if you want SEAD.
F-4G Wild Weasel - An oddity; SEAD, Sidewinders and Vulcan cannon with Good ECM. This is great at chopper hunting and killing low level radar AA like Shilkas.
This should get you started. I'll do a Soviet deck in a bit.