Here's the knowledge I've accumulated over the past 10 years about Remington 20 gauge hulls:
Gun Club - the lowest priced hull, 2% antimony content on average, steel base, loads very well.
American Clay & Field (ACF) - mid-range priced hull, 4% antimony content on average, steel base, STS quality plastic for greater reloadability.
STS - premium priced hull, 6% antimony content on average, brass base, high quality plastic for great reloadability.
IMO, and for a variety of reasons, the 20 gauge STS hull is the best out there for reloading.
If you have a MEC progressive loader, the primer insertion issue that has plagued many Remington hulls (mostly STS 28 & 410) has been corrected.
All MEC progressive loaders now come with a double clamp around the rammer tube to allow a greater insertion force to properly seat primers.
If you load on a MEC single stage press this has never been an issue. You just apply more down force on the handle until the primer is fully inserted.
Drilling primer pockets is a waste of time IMHO. if you have an older MEC progressive, just give them a call and order the short spacer, double clamp conversion parts.
I like 20/28 powder the best for loading 20 gauge target loads. Unique and Universal also work well when available. Good luck!