I have tons. TBH I am now playing Cypher Fantasy which is much more narritive, but for 5e here are the main ones:
No level dipping (must advance evenly), no unapproved subclass
Only one circus race per group (everyone else just human/elf/dwarf/halfling/gnome)
Only 1 hp/level after 9th level
Bounded Accuracy enforced - no magical item bonuses above +2, shields and ammo no bonus only powers, nothing stacks unless it says it does
Ability Score Increases happen at 4th, 8th, 12th, 16th, and 19th total levels, not by individual class.
Fighters gain their extra increases and the additional levels listed.
Sharpshooter and GWM nerfed to +3/+6, only one attack per round affected/
Channel Divinity uses are determined by total levels in classes with Channel Divinity, not by individual class.
Alignment is used to a great degree. No evil or CN alignments allowed in standard campaigns.
Players can choose to use their Dexterity modifier or their Intelligence modifier for their Initiative.
Any items that regain charges daily instead have a limited amount of charges when found, such as 1d20+5 for a wand. Some items that regain charges might also be 1/day use items instead.
No magical items that increase ability scores or that give class abilities.
At the end of a Long Rest, a character regains one hit point per character level plus its constitution modifier. The character additionally loses one level of exhaustion if they have any. The character also regains one Hit Die, and a character can spend any hit dice it has as if it had a short rest.
When someone drops to zero hit points, they gain a level of exhaustion, even if they get right back up from healing or assistance right away
Death save failures stay with a character until a long rest.
These work really well to eliminate some of the issues I have found in 5e, my group agrees. One player in my group has been around since the 1980s, another since 2000. Amazing group and amazing RP, great group mindset.