Welcome to Librarium Online!
I'm making a mainly Aspect Warriors army, and want to know the best craftworld for a mainly AS force.
I think Biel Tan since before the new codex for eldar came out, you could use the elite troops(howling banshees, striking scorps, etc) as your troops choice. If you read the eldar codex on pg 16 there is some info on Biel Tan.
btw i play biel tan aswell