Hi, first post but long time lurker.
First off let me state I really enjoy 5e, however there are a few quirks that I really dislike. Also, some of these are likely already mentioned but I haven’t yet had time to read through all of the 5e quirks listed in this thread.
1. The overnight heal is just ridiculous. In fact, in our group we mockingly call it “moonbeam” healing and have home ruled it out of the game, replacing it with Con bonus +1, min 1 healing per night.
2. Whack a mole healing in combat. Our group left that in, but added a level of exhaustion for each time a character is dropped to 0 HP.
3. Spells not listed by class, or even listing the classes that can cast them within the spells “stat block”.
4. The index is the Platonic form of how not to do an index. Enough said.
5. Magic item descriptions were not properly reviewed, leading to incomplete descriptions (see Bag of Tricks as an example).
6. SS and GWM feats are seriously broken.
7. Every class has a caster, resulting in magic not being special, even if some are seriously suboptimal (looking at you Way of the Four Elements monk.)
8. Weak skills system and tool proficiencies.
9. 6 to 8 encounters per day. That only makes sense in a dungeon.
10. While I love cantrips they are out of balance for Clerics vs using a melee weapon. Seriously, why would a cleric even bother to carry a weapon.
11. No speed factor on weapons. Weapons in 5e are rather dull and adding a speed factor would help differentiate them.
12. Save every round spells.
13. No real tank class. I’d love a class ability that allowed a character to really tank.
14. Intelligence is a dump stat. While this is a game, in what sort of twisted reality would intelligence be a dump stat, and don’t get me started on the multiclass shenanigans that can be played using this editions super casting stat, Charisma.
15. Darkvision’s ubiquity.
16. Every race getting only bonuses, and no gender differences. I loved 1e and 2e’s gender customizations, but in the PC era we live in I guess they had to go.
While these quirks really annoy me and the group I adventure with, we all agree that 5e has much more going for it than against it. It is the best version of D&D in a while, at least in our opinion.