I have been using webmin for some time now, however I miss the elegance and ease of WHM/CPanel combo I've had on shared hosting (and later dedicated hosting) platform.
Looking around the web, all I have found that is somewhat at the level of WHM/CPanel was webmin - but WHM/CPanel it is not.
Since I'm using this only for our projects, it doesn't matter in the end really. However, we do put our new customers on our servers too, so some sort of CPanel might be an easier thing for them to cope with (mostly going about Email accounts stuff and such).
Currently my stack is LAMP (CentOS and Ubuntu Server - several machines, probably ditching CentOS soon in favor of Ubuntu). There is a prospect of Python/Django instead of PHP, but it might take awhile.