Some others here mentioned space and weight, and those are certainly considerations. However I'd like to share something I've been doing that might also help you get more "real estate" out of a small space garden, and it may work well for your balcony.
I call it "stackable gardening." I start with a very large container (such a 45 gallon storage bin). This one goes on the bottom, and will hold my heaviest feeding plants, like squash or tomato. Then I place a second smaller container on top of the first one (grow bags or 5-gallon buckets work well) and reserve that one for something like carrots, onions, potatoes or peppers (take into account time of year). Finally, on top of the second container I will place one more, usually a small bucket or plant pot and reserve that one for plants that will remain compact, like strawberries, radishes, lettuce, or even petite ornamental flowers like violas (again, time of year is a factor in what I plant).
So in a nutshell, think of a pyramid. When you water the top plant, the nutrients in the soil (presuming you're using compost or fertilizing) will "leach" down through the second and into the bottom one. Each plant on top feeds the one below it. Discovering this was a breakthrough for me, teaching me to take advantage of vertical space since my horizontal space was severely limited when I lived in an apt. And I had the best veggies!
There are vertical stacking containers available online, some that even swivel (usually you see these demonstrated with lettuce or strawberries) but I found them to be expensive, wonky in heavy winds, and each compartment is the same size -- very small. Personally, I'm looking to grow food that is sustainable. And as much as I love strawberries, they won't keep us fed.
You may also need to consider water collection and use drip trays if your balcony is wood. In any case, I hope this gives you some ideas. Good luck!