Well, I can say we use direct admin exclusively for our customers that want a CP. I will go as far to say its the best CP I have used to date. I have used them all.. and it is fast as hell, very easy to configure (for admins and end users). I really can't say enough good things about it.
CPanel has got to be the biggest piece of trash I have ever used. We have a few customers that use it (bought it on their own) and they have nothing but problems with it. Its slower then living hell, and way too fucking big and bulky.
Ensim is pretty good.. haven't used it for awhile, but it was ok when we did.
But, in the end, DA has proved to be the best CP I have seen. All our customers that use it, love it. The guys at DA are great as well, they are very open to new ideas, and respond to questions, and or support at light speed.
They are fairly new (about 1 year) and I hope to see them take over the market.. they are well on their way, and it will be the only CP we recommend until I see something better come along.
Not holding my breath..
http://www.directadmin.com