I actually just finished translating VestaCP to Norwegian, I really recommend that you check it out, I installed it on a DigitalOcean droplet the other day, and I was quite amazed over how easy and painless it was to install o.o stuff just... works. check em out http://vestacp.com
Im using kloxo, its not hard to learn it. Webmin looks harder and more difficult to manage, but webmin looks to me to have bigger community anround and be more stable and mor elightweight. zpanel has low community around but is the most user friendly when one want to host website. i think.