I looked for a while and bought a DSA. Here's why:
The finish: parkerized receiver and steel parts, anodized lower (the lower is USA-made aluminum to save weight, not painted) New furniture. The Century FALs are painted to cover the sins of assembly. The furniture can be beat to crap. Looks like it should cost $200.
The parts: DSA, the barrel is USA-made, so are most of the other parts. All metric, all correct. Century internals are typically not spec and have to be "modified" to work. The parts are not properly heat treated and may work OK, for a while anyway. Century mixes inch and metric within the same rifle. If you have to change a part, don't expect a drop-in replacement. Check the ARS page previously noted for another opinion on these rifles. He will only build on DSA or Imbel receivers.
The company: DSA does FALs as its primary business. Service after the sale is great. Plus they're selling excellent metric mags for $8 each. Century service is essentially non-existent. Check their reputation on the FNFAL.COM boards. Not good.
In FALs you get what you pay for, nothing more. $1000 is pretty much a minimum for a good gun that will last 10,000 rounds. Pay less, and you take your chances.