Anyone ever compare these two?

I have used both quite a bit.
Sweets works good on copper.

If you mix Sweets with some other cleaners, they will corrode the barrel.

Also if you leave Sweets in the barrel,too long it will alos corrode the barrel.

Remclean Bore Cleaner, and like wise J&B, are a mild abrasive. They clean out copper and powder fouling.

Remclean, and J&B are the fastest and easiest way to TOTALLY clean a barrel IMHO.

After I am done with one of the above abrasives I flush out the barrel with Prolix.

When I just want to clean a barrel a "littls I use Shooters Choice, and then again flush out with Prolix.

Also if on a hunt or at the range, and I have fired the rifle and want to just "punch out" the barrel I just use a bronze brush and Prolix.

I have found in several different rifle barrels,everyone I have tried it in, if Prolix is the last thin I put in the barrel, and then dry the chamber and barrel out it does not change the point of impact.

Likewise if my barrel gets wet on a hujt, I just swab it out with Prolix, which gives it some rustprotection and does not change the first round out.

I have used DOZENS of bore cleaning products over the years.
Once I did an extensive test using a bore scope.

Remclean and J&B [I thin out the J&B with some Prolix], makes it easier to apply, cleaned the barrels, we were testing several different rifles, cleaned the barrels faster, easier, with less muss, less fuss, and with a lot fewer parches, and at a lot lower cost.

Just my IMHO.