Another vote for Better Than Bouillon from me. It's great stuff to have around, but I generally prefer homemade stock or broth. I find that the balance of most stock cubes or pastes or liquids is slightly off, depending on the brand. Maybe the yeast extract or a hydrolyzed vegetable protein that I can sometimes taste. I suspect the better tasting ones just balance the amount of these flavour enhancers well. In any case, I do tend to use BTB for gravies and sauces.
One consideration I use to decide whether to use stock or a cube, powder, or paste is, what do I have in the kitchen. Another consideration is how important is the flavour of the broth to the dish? Are there a lot of other flavours? Are they strong flavours? Is the broth going to be a star or is it just part of the orchestra of flavours?