Long tail at the moment, mostly because I don't yet have the capital to be where the money is. Chasing after kws which convert and have enough volume to make it worth it is not a piece of cake.
For the 50 bucks I make daily profit-wise with my less-than-impressive budget, chasing the long tail makes sense. There's plenty of room to grow, but in the end it's money that makes things happen.
You don't necessarily have to be brilliant to make it in AM: if you have the capital it takes to drive serious traffic to your offers, that automatically puts you in a position to negotiate higher payouts with the merchant (if your traffic converts, you can negotiate higher payouts even without a lot of volume but you wouldn't exactly be in the same position) and it's only logical to assume that the companies which send traffic your way will "appreciate" you more if you have deep pockets.
It all depends on what side of the fence you're on. Call it an unfair advantage the big boys have or whatever, nobody really cares. Deal with it or get lost, that's AM for ya.
JMHO