<a href=showthread.php?s=&postid=12434261#post12434261 target=_blank>Originally posted</a> by beerguy
Aperture is nice because you can import your existing iphoto structure directly into your catalog. The down side is that the RAW conversion isn't as good as some other options. I really like Aperture, and own it, but just can't justify using it because of quality issues. I prefer the output that I get from Lightroom.
I recommend downloading trial versions of both and see which one does a better job for you. You probably will need, at some point, a full editing package as well.
Cheers