I'm personally not a fan of the long URL's as I don't think they are embedded in visitors minds. I think visitors tend to forget longer URL's. There should be a happy medium, something that isn't too difficult to recall while being effective for SEO purposes.
You should always opt to get keywords into the URL's as it helps make the pages more relevant as well. It also bolds the search term in the SERP's if they match the query. All those visual aids help draw more attention to your listing.
Use the root domain for branding and consumer awareness. It's great if you can get one with keywords, but make sure you're doing it for the right reasons. I would say that you'd want people to associate your brand name with the search query, so the more opportunities to embed that connection the better. People look at both the keywords in the title tag, and the domain name in the SERPs. Having a true brand strategy is a long term play, and I think will pay off more in the long run.
Use keywords in the slug, since that helps with relevance and navigation. That will help people know where they are on the site, and help bots understand what the page is actually about.
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