It seems everyone here in Digital Ocean prefers Ubuntu.. Maximum of the tutorials are Ubuntu based.. So when I started, I started with Ubuntu but for some reason, zPanel was not getting installed under Ubuntu 14.04 and their support forum was saying that since zPanel installer presently supported Ubuntu 12 hence try it with Ubuntu 12..
zPanel did have a Ubuntu 14 installer but that was in beta and as I said, for some reason I could not get it running..
I am a linux noobe, so I started reading again about choice of OS and found, apart from DO, maximum of the web hosts runs CentOS and every paid of free panel supports CentOS..
I looked again and found zPanel did have a CentOS 6.x installer and I gave that a try with CentOS 6.5 x32 (running 32bit because of less RAM in my droplet).. Things went smooth.. Installation was successful and system running for last couple of months without crash or any reboot !!
What I see is, be it Ubuntu or CentOS, few commands are bit different but when Control Panel is running, from the point a view of using, you wont find any difference !!! So both are same in terms of usability !!
Being a Linux newbie, I tried both and personally liked CentOS hence went ahead with CentOS !!