What are the Pros and Cons to each one? Most of the time I am making vegetable soup.  Thanks 
It's hard to generalize them since within each category there are vastly different qualities.  Read the ingredients list carefully.     Bouillon: With some exceptions (buy these ones), you'll find most cubes contain little if any meat based stock, and are mostly salt, yeast extract, and dehydrated vegetables plus a load of MSG.  The best ones are the ones that are low in sodium and contain little fillers.  They also tend to be more expensive.  The good ones may allow you to provide a lift to the dish but not base a good dish on them. Powder: Here you'll mostly find corn starch, MSG, salt and some powdered vegetables plus thickening agents.  The chicken ones may have some real chicken broth based powder, and it's very hard to actually find beef stock in powder form.  While many restaurants use this type, the professional chefs avoid them and typically shake their head at dishes made using these.  Canned: you might get some honest stock in this form.  Again, read ingredients and check for salt. frozen stock: you can typically find honest beef and chicken stock in frozen tub containers in the freezer section.  They won't be as cheap as buying some soup bones or making your own. Tetrapack: In North America, you can find Pacific, and Imagine brand of broth in tetrapack form.  They (and a handful of others) do offer low sodium organic broth which tend to produce the best result from any store bought product and contain little fillers.  The 'major' brands also have organic lines but when you read the ingredients you'll know how little actual stock you're getting.  