You can use a Community, which provides point-and-click UI for building, capable of exposing Visualforce and Lightning Components, standard APIs for accessing the database plus direct UI access, sharing controls, profile permissions, etc, hosted by Salesforce directly, and licenses are pretty cost-effective.

You could also use NodeJS + Heroku/AWS/etc, but you'll need to write more code than hosting on Salesforce directly. You'll also incur a lot of extra costs for dynos/scaling, and you still need to figure out licenses. I think that, unless you're going for something far beyond what Salesforce can do directly, it's not a cost-efficient option. On the other hand, you might choose to use a Heroku app with database.com instead (another salesforce.com product) that's geared towards storage services without a UI; this would be more cost-effective in the long run.

Angular/BackboneJS/etc are also all possible. It's really about how much flexibility you need and the budget you have available. There's no one right answer to anything, but I would suggest you start with Communities first, as it is the easiest option to host on Salesforce. You can even use custom domains and custom branding.

I hope you find the above information is helpful. If it does, please mark as Best Answer to help others too.

Thanks.