The Thompson Center U-View Flex Loader comes with most TC muzzleloaders. You can have 3 pre-loads ready to go. You put your bullet in the tube point down. Then your pellets (pre-formed) and your primers go in the lid. It is pretty easy to grab a tube, drop it in, grab the rod, pack it down, and grab a primer to put in -- pretty quick.
Comparing this to the 4-in-1 Speed Loader, I can load both in about the same time. The U-View holds 3 rounds, compared to 1 for the Speed Loader. The Speed Loader gets the advantage if you measure out grains of powder vs. pre-formed pellets.
Since it comes with most TC Muzzleloaders, I give it the edge. Otherwise, it is about $3 - $4 cheaper as well.