I did quite a bit of reading on
http://www.fnfal.com before I bought my IAI M444 last year and I second the above reccomendation.
If you want an imported-cut-up-parts gun (~$750) as opposed to new manufacture (>$1000), DSA apparently puts the best one together, although last I heard, they were having difficulties with the ATF over their muzzle break. People also like DSA's new manufacture guns.
http://www.dsarms.com
Big things I remember were:
Guns put together by Century (a major importer) might have higher occurances of problems.
Metric pattern guns are easier to own than inch pattern guns due to availability of parts and magazines (although this might have changed recently).
Some barrels don't readily accept the standard bipod.
Some imports had the bolt-hold-open mechanism defeated.
Imbel receivers are top quality.
A few mags can give you a pretty decent headache if you don't use a proper hold (personal experience).
Few other guns have a bigger "cool" factor.
My M444 is the pride and joy of my collection (I know you guys with >$1k guns are laughing at me for saying that)