Depends on what you intend to do with one. If you intend to overclock your system, then they should have good power delivery and a beefy heatsink to dissipate the heat off the VRM's. If you're looking for top notch audio, it should have high quality audio capacitors or a top of the line audio codec onboard. If you intend to run off the iGPU, make sure it caters to the connection you intend to utilize when connecting to a display.
That being said, since your question was vague and to an extent demanding a lot from a post, what are the specs to your intended/proposed build?