boards has objectively one of the best messageboard/imageboard UI (I know it's not an imageboard but I'm including imageboards when comparing the UIs). I think that 4chan has a decent UI and I like it when message/imageboards resemble old internet user interfaces. Hikari3 has that "classic internet" look however it's super overstimulating and there's way too much going on. Boards however, is able to keep the old internet look or aesthetic or whatever while still being functional and not an eyesore.