Son, just because you're condescending doesn't mean you're correct. At the risk of derailing the thread, I'll explain my position.

I think the 3-4 allows for more flexibility and is more disruptive. The 3-4 features four linebackers, who are the best combination of size, speed and athleticism on the team. They can line up in various locations to confuse the opposing quarterback while still being in sound defensive positions. The featured pass-rusher is the weakside outside LB, who is quicker that a DE and much quicker than the offensive tackle assigned to block him. And often the weakside outside LB lines up on the line in a lineman's stance, so it presents itself as a four-man front but is more flexible than a 4-3. For example, when you run a zone blitz, the "lineman" who drops into coverage can be a quicker LB rather than a slower DE. When you go into nickel situations, a DB replaces an LB, but you still have three LBs on the field as opposed to only two as in a 4-3.

From a recruiting standpoint, it's a matter of numbers. I'm going to base my formulation on personnel needed for a two-man depth chart.

DBs are the same in both schemes, so that's irrelevant. Both the 4-3 and the 3-4 need four quick, speedy cover corners, two strong safeties who can play the run as well as cover wide areas of the field and two free safeties who can play center field and break on the long ball.

LBs, as noted, should possess the best blend of size and speed. Obviously, you need to recruit six LBs for the 4-3 and eight for the 3-4. In the 4-3, the middle LB has to be a big, fast, terrifying monster. In a 3-4, you have two inside LBs who can be slightly less terrifying and cover more ground. You don't need to have a Butkus or a Ray Lewis in a 3-4. More on LBs in a moment.

The defensive line is where the key difference is, and it's probably harder to recruit great linemen than it is great linebackers, primarily because 6-4, 250-lb guys who can run are easier to find than 6-7, 300-lb guys who can run. A 4-3 essentially needs eight of those 6-7 guys, at least one of whom has to be a DE who can fly to be the featured pass-rusher. A 3-4 requires two nose tackles who must be huge but don't necessarily have to be the greatest athletes because their job is to occupy two offensive linemen. You need only four of those 6-7 guys, and none of them have to be the monster pass rusher because that job belongs to the weakside outside LB.

So, in sum a 4-3 demands twice as many 6-7 guys who can run. It's a lost easier to find two huge but not-necessarily athletic guys to play nose tackle and a couple more LBs than it is to find four additional 6-7 linemen.

That's why I think it's easier to recruit for a 3-4 than it is for a 4-3. Of course, it doesn't matter what scheme you use if you have inferior talent.