Webmin is really the best control panel out there, beating both other free and paid alternatives. The only drawback is that it doesn't support mass/virtual hosting CP delegation. But from the sound of your post, you don't seem to be doing hosting.
Take the time to learn webmin, it is well worth it. (I know it was for me). Besides, the interface is very cleanly seperated into catagories and modules, so it shouldn't be confusing. Also, you get a lot more control than another other control panels.
Ensim is extremely difficult to get rid of because they install all sorts of custom RPM packages. Plesk is good to install and uninstall, and they even have a free 1 domain version. If all your admin work is just going to be reboot/set time, then the free 1 domain version will suit your well. However, no type of hosting is possible, since it also has a 1mailbox limitation. H-sphere is best for multi-server environment, and from what I heard, takes some learning time.
Also, though H-Sphere is new, their support is top rate compared to other control panels. They have staff actively patrolling and helping people on their forums, which is far more than I can say for Ensim. Also there are plenty of people willing to vouch for it.
External licences (you own it 100% and can use the licence where you want):
From a reseller these would be $4 each. Each licence gives the right for the person it is used for to host 10 sub-domains (though this part wasn't 100% clear to me, it might actually be 10 domains or subdomains).
Internal licences (from a certain host/datacenter)
$2 each, host/datacenter retains ownership.
To have it installed by a psoft tech is $100 per server or cluster, but you can install it yourself (which they say is rather complicated). Maybe a reseller would be able to beat this price.
You can only buy in packs of 100 licences from psoft directly @ $4.50 per licence. Resellers tend to offers smaller packs at a slighly cheaper price per licence.
H-Shpere has great financial advantages if you don't intend to put 1000 sites on a server. If you do intend on hosting hundreds and hundreds of sites on a server, H-Sphere loses this advantage and becomes expensive compared to alternatives.