What companies sell good rear end pkgs.??

Wonder what ya all think , I am going to go to 4:10`s or perhaps a little smaller what companies should I look at as far as QUality goes etc.???
I wd. want to build a complete kit not including the posi??
I should note this is for a daily Driver as well..
Thanks

Are you looking to upgrade to a 12 bolt, 9" or just the internals of your current 10 bolt?