Smokey and I teamed up to publish NL-Only and AL-Only position rankings for those of you in "only" leagues. They aren't as popular as mixed leagues, but I play in more "only" leagues than mixed leagues, and always have. I think "only" leagues require you to do a bit more homework to find that corner infielder or 4th-5th outfielder who could end up playing everyday.
Anyway, here are our 2013 rankings for AL-only and NL-only leagues:
NL/AL-Only Position Rankings
If you are looking for more AL/NL-only league rankings, there is only one spot on the internet that is home to all the rankings you will ever need - Fantasy Rundown. They provide links to all the other fantasy baseball sites everyday for one-stop shopping. Check them out.