Sumo Deadlifts or Conventional Deadlifts - Which one should I do?
Both! Do Both!
Now, if you're training for a powerlifting meet or are looking to maximize your total strength on a particular deadlift, then focus on the one that allows you to lift the most weight! People are different and have different leverages due to limb length and muscular preferences. Do the one you can do with the most technical proficiency!
However, if you're just looking to build muscle, get overall strength and muscle, both Variations have their benefits!