With experience over time I learn about new technologies. I'm going to touch on a few of the new things I'm starting to favour in preference to the old favourites.
IPv6 vs IPv4
Internet addresses of the DotQuad 192.168.1.1 variety are an extremly scarce resource these days. So over the last 10 years, the IEFT and other bodies have developed a new version of TCP/IP, IPv6.
In September 2010, I developed a training course for IPv6 which you are free to download and read through. The march toward IPv6 is inevitable, and should be ignored at your peril.
Nginx vs Apache
Apache is without a doubt the most popular web server on the Internet, and with good reason. However I've found that if you're running a server that can experience extreme load conditions, nginx handles this much better than apache. Apache has a habit of forking new processes beyond the resources of the machine and can cause a system crash or just so much disk swap that it may as well have crashed.
Apparently it is rumored that nginx was written by the Russians for serving porn sites, but it is clear that they did a good job. Nginx can also be use very well as a reverse proxy front end load balancer to another web server in the back end.
Mikrotik vs Cisco
Cisco have virtually priced themselves out of the low end router market. Enter a small company from Latvia, which was (and still is) very much focused on wireless router technologies.
In doing so, they have created a router operating system for X86 and their own hardware, which provides a bang for buck which is unprecedented in the router market.
$80 will get you a routerboard that can do MPLS & BGP.
I'd almost go as far as to say that Mikrotik have gone too far the other way and should charge more for their products.
You can download RouterOS from http://www.mikrotik.com/download.
Be sure to create yourself a free trial license key.
MariaDB vs MySQL
When MySQL got bought out by SUN, no-one really cared until Oracle bought SUN, which meant that the worlds favourite free database was now owned by the worlds biggest database giant. Some folk are worried about what might happen to MySQL under Oracle control.
Monty, the original author of MySQL has a forked version of the product named after his daughter which features many of the patches done by Percona, Google and others. MariaDB is now installed in a Multi-Master cluster at BACB, my primary workplace.
Exim vs Postfix
It was over ten years ago when I transitioned from Sendmail to Postfix. At least postfix was a drop in replacement which worked with the same access lists etc. Times have changed and spam has become ever more present and people are wanting to run many more domains on a single server and I am impressed by the capabilities of the newcomer Exim.