My 20ga USH likes most everything. The first year I used it I used the Rem Ultra Core-Lokt, was getting outstanding groups from 3/4" to 2". I shot a big 8 pt high through both shoulders with the bullet just under the hide on the far side. The the Win Partition Golds, Win Platinum Tips, Fed Barnes, Rem Copper Solids and Lightfields all shot great too. The next year (2004) I bought more of the Rem Ultra Core-Lokt (different Lot #) and they didn't shoot worth a hoot, 5" range. So the Win Partition Golds were what I ended up using, they were grouping in the 1-1/4" to 2" range. I also used them this year (2005). The Platinum Tips are in the 1700 fps range and also shoot very well.
The lightfields shoot very well and kick much less than the 1900 fps slugs do but hit about 3" lower at 100 yds with my setup (Bushnell Trophy in Burris high rings). The nice thing about that though is for under 100 yds you can use the Lightfields and for 100 to 150 yds you can use the Win Partition Golds. One thing about the Lightfields though is they shoot about 6" lower on a clean bore and shoot good groups after the bore has been fouled in my gun. I always hunt on a fouled bore, after my final sight in it stays dirty until after season.
The best thing to do would be to try them all and find out which shoot the best in your particular gun, it does get expensive though.
One thing though if you find one that shoots well and you plan on using it. Go back to where you bought them and buy all of them you can afford with the same lot #. The lot # is usually stamped or printed on one of the flaps. After shooting slugs for over 30 years, I have found that Lot #'s do make a difference in slugs. You may get lucky with a different #, but don't shoot all of one lot # practicing and then go buy another lot # to hunt with and assume they are going to have the same POI.
One more thing, the barrels do get warm if you are shooting too fast. If you want your best groups and want to know where your gun hits on a cold barrel, you need to SLOW down at the range. Break it open and it will cool much faster between shots and use the rubber O-ring on the forend lug. If you pop one off right after another you will have a warm barrel and most times it will have a different POI. Good luck!