This is a rough comparison table of all the "popular" ECS frameworks written and used in C#.

Table

Support...
:heavy_check_mark: = Full
:heavy_check_mark:Ex = Full with extension
:heavy_minus_sign: = Partial
:x: = None

Feature	Leo ECS	Leo EcsLite	Default Ecs	Svelto .ECS	Morpeh	Unity ECS	Entitas	chrome alex /ecs	Nano ECS	Ego CS	actors .unity	Feature
Archetype based	:x:	:x:	:x:	:heavy_check_mark:	:x:	:heavy_check_mark:	:x:	:heavy_check_mark:?	:x:?	:x:	:x:	Archetype based
Filter/Query operations	Has/Not (Inc/Exc)	Has/Not (Inc/Exc)	Has/Not Or/Nor		Has/Not (With/ Without)	Has/Not/Or (All/Any/None)	Has/Not, Any (All/None)	Has/Not, Any	Has/Not (With/ Without)	Has	Has	Filter/Query operations
Components Type support	struct	struct	struct /class /interface	struct /interface	struct	struct /class	class	struct	class	class	class?	Components Type support
Code Generation based	:x:	:x:	:x:		:x:	:x:	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:	:x:	:x:	Code Generation based
Dependencies	None	None	None	None	:heavy_minus_sign:Unity Odin Inspector	Unity	:heavy_minus_sign:Unity	Unity	Unity	Unity	Unity	Dependencies
Engine agnostic	:heavy_check_mark:	:heavy_check_mark:	:x:?	:heavy_check_mark:	:heavy_minus_sign:	:x:	:heavy_check_mark:	:x:	:x:	:x:	:x:	Engine agnostic
Custom Engine Support	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:		:heavy_check_mark:	:x:	:heavy_minus_sign:	:x:	:x:	:x:	:x:	Custom Engine Support
Threading support	:heavy_check_mark:Ex	:heavy_check_mark:Ex	:heavy_check_mark:		:x:		:heavy_minus_sign:	:heavy_minus_sign:?	:x:	:x:?	:heavy_minus_sign:?	Threading support
World Events/Messages	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:		:heavy_check_mark:	:x:?	:x:		:x:?	:heavy_check_mark:	:heavy_check_mark:	World Events/Messages
One-Frame Components	:heavy_check_mark:	:heavy_check_mark:			:heavy_check_mark:EX	:x:?	:heavy_check_mark:					One-Frame Components
Dependency Injection Support	:heavy_check_mark:	:heavy_check_mark:	:x:		:x:	:x:	:x:	:x:	:x:	:x:		Dependency Injection Support
Shared Resource	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:		:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:				:heavy_check_mark:	Shared Resource
Thread-safe	:x:	:x:	:heavy_minus_sign:	:heavy_minus_sign:	:x:	:x:	:x:	:x:?	:x:	:x:	:x:?	Thread-safe
Reactive System	:x:	:x:	:heavy_check_mark:	:heavy_minus_sign:	:x:	:x:?	:heavy_check_mark:		:heavy_check_mark:		:heavy_check_mark:	Reactive System
Multiple components of same type on entity	:x:	:x:	:x:	:x:	:x:	:x:	:x:			:x:		Multiple components of same type on entity
Components can live without entities	:x:	:x:	:heavy_check_mark:	:x:	:x:	:x:	:heavy_check_mark:					Components can live without entities
Entities can live without components	:x:	:x:		:x:	:x:	:heavy_check_mark:	:heavy_check_mark:					Entities can live without components
Unity Editor View support	:heavy_check_mark:Ex	:heavy_check_mark:Ex	:x:	:x:	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:	:heavy_check_mark:	Unity Editor View support
Unity Editor Full Integration*	:x:	:x:	:x:	:x:	:heavy_minus_sign:?	:x:(WIP)	:heavy_check_mark:		:heavy_check_mark:	:heavy_check_mark:?		Unity Editor Full Integration*
Unity Burst Compatible	:x:	:heavy_check_mark:Ex	:x:	:heavy_check_mark:	:heavy_minus_sign:	:heavy_check_mark:	:x:	:heavy_check_mark:	:x:?	:x:?	:x:	Unity Burst Compatible
Unity Jobs Compatible	:x:	:heavy_check_mark:Ex	:x:	:heavy_check_mark:	:heavy_minus_sign:	:heavy_check_mark:	:x:	:heavy_check_mark:	:x:?	:x:?	:heavy_minus_sign:?	Unity Jobs Compatible
License	MIT	MIT	MIT-0	MIT	MIT	Unity Companion License	MIT	MIT	MIT	MIT	MIT	License
Last Major Version Release Date	Feb 2022	Feb 2022	Feb 2022	May 2023	May 2023	Sep 2022	Sep 2022	Sep 2020?	Dec 2019	Mar 2017	Jul 2020	Last Major Version Release Date
Feature	Leo ECS	Leo EcsLite	Default Ecs	Svelto .ECS	Morpeh	Unity ECS	Entitas	chrome alex /ecs	Nano ECS	Ego CS	actors .unity	Feature

*(Unity Editor) Full Integration means that systems & components can be made, disabled, enabled, and configured in Unity Editor.

How can I contribute?

Find a table cell (or multiple) that isn't filled out, and make an issue/pull request about it. While stating why it's true (explanation doesn't have to be very sophisticated or sourced/grounded, most of the time).
OR
Find a table cell (or multiple) that has a quesiton mark, and source why it's true/untrue with an issue or pull request.

FAQ

Q: Why not split the table?
A: I think the table isn't big enough for a split to be valuable, and it's easier to check for all the features you'd want with one glance, instead of going back and forth between two tables.

Q: xECS isn't here, why's that?
A: Idk, ask about it in a new issue, it might be too niche, or something.