I'm surprised at the www supporters. Do not do this. Down the road, you will want to use subdomains (app.example.com, dashboard.example.com) and choosing www out of the gate will make it more complicated then it's worth. If HTTPS is required, then a certificate with www will always get in the way, get a non-www and add a subject alternative name, or get a wildcard.<p>It is much, much easier to redirect all non-www traffic to www if a subdomain is not specified then otherwise and a wildcard or SAN-enabled certificate will make it much more flexible in the future.
With "www". That makes it a lot easier to add in CDN support, DNS based load balancers, and a ton of other tools down the line.<p>Why? Because you need your domain root to have all sorts of other stuff in it- MX records, SPF keys, and various other things. A lot of CDNs and DNS based tools work really well by utilizing CNAMEs, which you can't do on the root. Putting your website on "www" keeps is as a separate isolated service and makes adding those services easier down the line.
As a technical person, I can recognize a URL when I see it and prefer the non-www version for brevity's sake.<p>But many non-technical people cannot understand if something is a website URL without the WWW in front of it. It's probably best to add WWW if your target audience is normal humans.
Is there a reason both aren't registered at the same time? i.e., why does it matter which one I point to in a url/link/script/etc.?