I have built Jegs cages, comp cages, S&W cages, and an Art Morrison, as well as a couple of custom hand bent with a JD2 bender. The higher price kits, do fit a little better right off, but I have never had one that didn't fit at all.
None of the pre-bent ones are perfect, but for the price you can't go wrong. I will be using a Jeg's one with the 4 link rear kit, and possibly the front strut kit, in my upcoming project vehicle. If you have a competent welder / fitter they are safe, they pass tech, and they let you spend money else where. Like anything, you get out what you put in. Spend the time fitting, and tweaking it and it will fit well, if you try to just throw it in... You get the idea.