Notes
The best beef bouillon is the one you make from scratch. This involves cooking down beef scraps and bones into a rich broth. If you are using bones, paint them with tomato paste and roast them for a short time first.
You really have to like a Bloody Bull or other drinks that have beef bouillon in them if you make the beef bouillon from scratch. More power to you if you go this route.
But if you're after premade bouillon, there are viable choices out there. Stay away from the canned stuff--too much salt and not enough flavor. Also, the Knorr and Tones cubes are still too salty, though they are better than the canned stuff.
The best premade beef bouillon I've found is made by Penzeys Spices and is called Beef Soup Base. It is a jar of beef bouillon that you reconstitute with water. It has far less salt and far more beef flavor than the other options.
Penzeys Beef Soup Base