NGINX.
Not to say there aren't viable configurations for Apache, like MPM, and other candidates for server software. When it comes to PHP, nginx with PHP FPM (which is now built in) is very fast.
Personally I believe that tales of balanced "pros and cons" are almost entirely synthetic. Apache, in the hands of a very experienced admin, can do well at threading but even at it's best is a resource hog.
PRO-Apache:
1. Deeper configuration scripting options for less common networks, caching scenarios and services.
2. More tutorials online. Familiar, respected.
PRO-NGINX:
1. Very clean architecture, fewer things can go wrong once you've got it right.
2. Massively threaded.
3. Lightweight memory footprint and processor usage
4. Far above apache in serving static content
5. Can use the more common apache configurations and has some unique abilities.
6. Modern concerns taken into account during design of NGINX
ANTI-Apache:
1. Bloated. SO SO bloated. Do not underestimate the level of resource drain that is caused in the majority case. Experienced admins may fine tune it but there's only so much you can really do. You need more CPU and more RAM to run the same site at the same traffic level.
2. Complex. While more people are used to Apache due to its age and near monopoly early on, the average admin of those I've met are not masters of it. There are many nuances to any web server, but especially Apache imho.
3. Apache's detailed config scripts are both a pro and a con. You don't want to have to debug a configuration. While things like "EasyApache" exist, most scripted installs are not optimized for your situation.
4. Declining support, industry slowly moving on.Even Apache 2 is based on partially outdated code.
5. Totally subjective, but Apache was once my favored server. I can hardly stand to use it anymore, I feel that NGINX has spoiled me.
ANTI-NGINX:
1. Slightly less community support / tutorials online. Not in short supply by any means, though.
2. If you are accustomed to Apache already, you'll have to learn a little bit.
3. Some of the NGINX nuances are annoying, like sockets sometimes need. a little help depending on which distro you use. Nothing major.
4. NGINX Pro. AFAIK Apache is 100% open source. NGINX is trying to monetize the product directly, which means some good features may be withheld from the base offering. It seems this mostly relates to cloud clustering however which neither do out of the box anyway.
