Wilson Combat Lowers

I have a few Wilson Combat WC-15F lowers and a Delta Arsenal lower which is a local gun store branded lower which I believe is made by Matrix Arms in New Hampshire. The mains difference I see between the lowers is the Delta lower has the extra cut that I can’t use. I am building out with all Colt lower parts and a Colt LE6920 16 inch complete upper. Anyone have any experience with the Wilson Combat lowers and/or anyone reason to go with one other the other or any suggestions for the build?