I’m personally a big fan of Advantage/Disadvantage but I’d really rather 5E picked one mechanism and stuck with it - for instance the added or subtracted dice of Bless/Bane or Bardic Inspiration.It’s not just the die roll but the all-or-nothing element. Fundamentally, I think 5e went about reducing mod bloat entirely the wrong way. If I really wanted to run it, I'd probably see if SotDL boons/banes would port over without breaking anything.
(I can totally see why you’d do that - it allows granularity for increasing the size of the Inspiration die and also the bard doesn’t get to sing “stab, stab the ogre in the kidneys” to help the rogue backstab people - but I’d probably still prefer one mechanism.)
If you like you could just say Advantage/Disadvantage is +/- d6 to keep it in line with everything else, or maybe scale Advantage/Disadvantage dice with level like the proficiency bonus (d4 at 1st to 4th level, d6 at 5th to 8th level, d8 at 9th to 12th, etc.).