I'm a fan of a fastcgi php-fpm server and a nginx for static assets / reverse proxy for php- rpm :)

Been testing nginx on a few WordPress and Magento sites, and the performance difference has been dramatic

I always use Nginx.
It is fast and allows to do some neat tricks like SSL preread.

lighttpd is pretty small and convenient, yet still has quite a few features that can be enabled as modules like apache. It has a pretty good security record. I see it a lot on embedded linux devices, but I also install it myself on workstations when I want a web server for local development because it's convenient. Also have good experience with it on light usage public webpages, but I'd probably pick nginx for something with high enough volume for performance to matter.

Very much so. Magento is still a pig though. But there's no web server that's going to change that