I haven't tried Firefox, but I can tell you what I do in Opera: default settings are restrictive, then when I want to enable something on some site, I go to "Edit site preferences". The site name e.g. news.ycombinator.com is already there. And imagine I want to allow everything on the whole ycombinator.com, I just delete "news." then allow what I want (e.g. JavaScript).

That way I enjoy the quietness (by default) of the sites and the higher security of browsing. When I really, really need sites which depend on too much moving parts I start some other browser, but for day-to-day browsing I enjoyed not having to install any extension but still having something like "noscript." If Opera fails, I'll have to discover how to get similar functionality on some other browser.