In response to this Reddit post.
I use Notion's web clipper, which is pretty close to optimal ease of entry.
About once a week, I look at all my clippings and see which ones I actually want to read and move them into a reading app. This cooling-off period is critical! Otherwise I overwhelm myself with information - it's hard to resist the temptation to be a digital hoarder.
The reading app I love is MarginNote 3 for my iPad. Related documents are grouped together and my highlights can be drag-and-dropped into a mindmap that unites sets of related documents. Nodes in the map can be exported to Anki. It's brilliant - my syntopic reading has skyrocketed.