App-based platforms such as ARKit and ARCore require native apps for iOS or Android. WebAR, on the other hand, runs directly in the browser - without installing an app - and therefore lowers the barrier to entry.
Advantages: Cross-platform development (Android, iOS, AR glasses), large selection of plugins. Disadvantages: relatively high complexity for beginners, dependence on native SDKs.
Unreal offers excellent graphics quality and visual blueprints for AR development, but is technically more demanding and less mobile cache-optimized than Unity.
WebAR does not require any app downloads, can be used on any device and is ideal for marketing campaigns. Disadvantages: often chargeable, lower graphics and tracking quality compared to native apps.
The Mixed Reality Toolkit (MRTK) was once an important basis for HoloLens applications, but is hardly developed any further today and is primarily historically relevant.
Lens Studio (Snapchat) enables simple AR experiences without programming knowledge and is specially designed for Snapchat. Spark AR (Instagram/Facebook) has been discontinued and is no longer being actively developed, so Lens Studio is currently the more sensible option.