You should look at webmin and/or webmin/Virtualmin. I have tried a lot of control panels over the years and I like webmin/Virtualmin. You get the best of both worlds. I find that Plesk is too heavyhanded on what it does to the server. I also think it is too heavy on resources. I manage a few Plesk servers and I hate when I have to go into them.
Virtualmin is an additional layer to webmin; it allows you to set up virtual servers (think cPanel on WHM). If you are not wanting to host virtual servers for others then webmin is all you need. You can run as many sites as you need with just webmin but they are not isolated from each other; Virtualmin is like cPanel in that each virtual server is isolated from the others.