For a complete one-off, plain JavaScript and DOM. For a small, simple project, MooTools. For a large project, Closure Tools. jQuery's not a good choice for anything I work on, and its "God Object" API makes for repugnant code.

I would use Ender and pull together various micro-libraries/modules.

http://ender.no.de

That is very interesting. It looks like they even have a "starter pack" that approximates much of what jQuery does: http://ender.no.de/#jeesh

Thanks.

I winder how it well it works with SVG?

MooTools. Dojo. The herd has been thinned a bit over the last few years.