[Pogo27]

4-3 is best of those three against the run.
4-2-5 is best of those against the pass.

3-4 is a pretty good balance.

4-3 requires you to have good run-stopping DTs, and good coverage LBs.
4-2-5 needs usually a good, hard-hitting CB to play in the 3rd CB role.
3-4 needs two OLBs that are good pass rushers. 3-4 also probably needs the most variations on the play calling. It's a blitz-heavy scheme the depends on confusing the QB with multiple blitzes.

3-3-5 is also out there, and it's not terrible. In fact, if you've got a great DT, 3-3-5 is arguably a better option than 4-2-5 as it gives you that much more speed on the field.

In both the 3-4 and 3-3-5, your DT probably should be your best overall player on the D, especially in the 3-3-5.

I'll say this, 32 NFL teams use 3-4 or 4-3 most of the time. And most of the 3-4 OLB is a hybrid DE/OLB. It's almost like a 3.5-3.5-4.

Ultimately though, choosing your defensive scheme needs to depend on the personnel you have on campus. I prefer to run the 3-4, and I try to recruit for that, but I'm not afraid to change my defensive playbook on an almost yearly basis to suit my team.