Most of the PSUs manufactured today do come with the GPU connectors; however, not all PSUs are good. Here's a list of quality manufacturers:
2. Cooler Master
Keep in mind that the output (wattage) isn't as important as the load (amps). If you're going to install a GPU that requires the 6/8-pin plug, you'll need a PSU that has at least two dedicated +12V rails, with each rail able to support the amperage requirement for your GPU.
My suggestion is to find out the requirments for the GPU, then base your search based upon your budget, while keeping in mind the manufacturers mentioned above. Also worth mentioning is that PSUs with at least 80+ Bronze Certified are viable candidates.