Likes and dislikes by edition
In general against all editions.
LIKE: All of the "lighter system / quicker to run / doesn't get in your way / trust the DM" stuff. Adv/disadvantage, theater of the mind, lighter rules, etc.
HONORABLE MENTION: I like the casting spells at different levels, I think that was originally back in a Wheel of Time expansion for 3.0 so I don't know if that counts as a change.
DISLIKE: Skills vs. tools.
DISHONORABLE MENTION: I love the concept of concentration but dislike the implementation in that it adds a lot of extra rolls in combat.
Vs. 4e:
LIKE: No more ridiculously large list of individually nuanced powers to be considered every action (at paragon or higher)
HONORABLE MENTION: Circles aren't square!
DISLIKE: Removal of some common standardizations, like Bloodied and other shorthand.
Vs. 3.x:
LIKE: Ease in creating high level foes and NPCs. And getting away from crazy prerequisites for feats/paragon classes.
HONORABLE MENTION: Take the super-flexible multiclassing system and make it much less abusable by changing what you get at 1st for skills/proficiences and moving a lot of class abilities to higher levels.
DISLIKE: Standard monster abilities (all undead are immune to mind effecting, etc.) Consistancy made hard-learned player lessons more applicable.
DISHONORABLE MENTION: More casting differences between wizard and sorcerer made them more unique.
Vs. AD&D 2ed:
LIKE: More flexibility in character creation. (Alternate: No rampant power creep like Skills and Powers).
DISLIKE: Hmm.
Vs. AD&D:
LIKE: Much more balanced.
DISLIKE: Not getting exposed to this with childish eyes full of wonder to Gygax.
Vs. Red-box BASIC:
LIKE: PC flexibility and spells.
DISLIKE: 5e takes slightly longer to run combats.
