Mustache is pretty solid, but I found it to be a little too hardline about the "logicless template" thing. For example, it doesn't offer a lot of small niceties you'd hope for in a templating system, like an "else" statement. You have to do dumb stuff like this all the time:
{{#if foo}}
<span>foo is set</span>
{{/if}
{{^if foo}}
<span>foo is not set</span>
{{/if}}
Instead, I'd recommend Handlebars which is built on top of Mustache, but adds some nice features like custom helpers and better context-switching support.