Most of us guitarists ignore the influence of pick to the tone.
But here is where it all begins! Not at the strings, pickup, guitar or Amp - the pick is the first thing - and it's in your hand! So don't save your money and ignore even these little things in guitarist-life.
Let's see: A good pick needs a good grip, so you won't lose it.
It has too feel ergonomic, so it will be one with your fingers and won't get tired of holding it.
It should hit the strings hard enough without stopping you motion.
It should release the strings fast, rolling-off and without killing the tone.