Why would ISPConfig 3 benefit me over another setup of the same? Finally, I know Debian is basically one of the best server distros out there, BUT can Ubuntu Server be just the same with ISPConfig?
ISPConfig 3 allows you to manage multiple servers from one controlpanel as needed for a professional ISP, e.g. 5 webservers, 2 mailservers, 2 DNS Servers and 2 database servers. Additionally, ISPConfig 3 is very easy extendable, themeble and has a remote API which allows the integration into other software or CMS systems.
Debian is a better solution for servers then Ubuntu in my opinion.