Hi,
I'm still new, but I seem to be an oddball here. All of my games have been versus the AI and I've personally found defending vastly easier than attacking. I've lost only one defense and maybe half of my attacks (mostly when I chose armor, which is why I was seeking advise in another thread). I'm playing my first defense versus a human which I'm expecting to be much more dificult than versus the AI for obvious reasons.
I think the game is balanced just fine. I can give the advantages of defence, but most people here have probably heard them. That said, I would suggest playing on small map sizes for QBs as it defenately helps the defence to maintain a more cohesive force. I think one of the arts to defence is unit purchase.
I do find certain units invaluable on the defense, with my number one buy as the German 88 Flak. BEST ALL PURPOSE DEFENDER. For 80 some points you get a gun capable of taking out a lot of the enemy armor, great blast value vs infantry, and AA protection thrown in for good measure. The ammo allotment is evenly split between HE and AP. Snipers are also a very good buy, especially in assaults as they can be great advance warning units and provide suppresion value. And of course, AT bunkers are very usefull. Don't bother with the 88 bunker unless you think your enemy will come with a behemoth. MGs are much more usefull since their primary drawback of being SLOW walkers doesn't affect them as much. I could go on, but I've probably drawn enough flames messages already.
Pete
(who will probably be eating crow after getting trounced in his first defence vs a human)