[CentOS] Centos 7 and priorities

I've recently changed to Centos 7.
My recollection from C6 is that a couple useful repositories
need yum priorities to prevent some mixups.
I do not remember what they are.  My C6 is gone.
Google has not told me what C6 repositories were.
In the near future, I will be installing nux and epel.
My understanding is that they do play well with each other and with base.
Are there common useful C7 repositories that need
help playing well with the aforementioned repos?

Is there a FAQ or a FM on this?

-- 
Michael   hennebry at web.cs.ndsu.NoDak.edu
"Sorry but your password must contain an uppercase letter, a number,
a haiku, a gang sign, a heiroglyph, and the blood of a virgin."
                                                              --  someeecards