I have seen DirectAdmin (Paid) working really good with even 512MB droplet but then again that is a paid software and I found control panel is something which I would rarely use once things are fully setup..
Later on I switched to zPanel and found to be good enough to get my work done.. Comes with everything, php, apache, mail server, MySQL and all.. Will give you all the tools like file manager, phpmyadmin and such like cPanel does..
If you plan for business use, then I would suggest opt for DirectAdmin since I found it to be resource friendly compare to cPanel and cheaper..
If you want to host your own websites only, zPanel would do the job..
Please note, zPanel project is presently sold and the entire team moved to Sentora, so install Sentora which is upgrade of zPanel..
I also tried one more panel, that is CentOS panel.. It is also good one but fairly new so many features are still missing but will get your job done..