Depends on what you plan on shooting and what lighting effects you want. I have 2 soft boxes, one reflective umbrella and a small soft box for my 580ex II flash. I use them for boudoir shots only and I do a lot of mood lighting. I only purchased my setup because I got an astounding deal but I am more of natural light or available light shooter. I think soft boxes are no brainer if you want to do portraits, you can buy different sizes and your choice of light power is almost limitless but 250w should be good for general portraiture needs and a 22" x 16" soft box with a light stand would be my first light purchase but lights are very pricey so it also depends on your budget and I have wireless system for my setup. I am not the best to answer this as I use them for one reason only and I like very soft lighting for it. So what do you want them for? and do you have budget constraints? I mostly use one soft box and my reflective umbrella with 250w heads or just a single soft box and it depends if I have one or two models in the shot and the effect I want to achieve, for me right now it is just playing with lighting and getting used to using light source outside of what is available and I still find I shoot about 50% of the time with available light still. As I said I am not the best person for this topic but can tell you what I use, and it is only recently I have used any lighting at all and if not for the book I want to do I would not have bought lights at all and why I spend all that money on fast glass. I hope someone has better and more info than the pittance I can give you.