Which control panel should I opt for - WHM/cPanel or Plesk/WebsitePanel?

The type of control panel that comes with a particular web hosting package is already fixed. You cannot change it. You can however pick that particular type of hosting which comes with your chosen control panel.

ZNetLive offers three types of control panels at present- WHM or cPanel, WebsitePanel and Plesk. (Technically WHM and cPanel are different control panels but they are written as one as they work together.) Windows hosting comes with Plesk (for resellers) and Website Panel (for shared, VPS and dedicated servers), whereas, Linux hosting comes with WHM/cPanel control panels.

The main difference between the three control panels is the way in which they are organized; otherwise they perform similar functions- of configuring the website, viewing statistics, email accounts and viewing files uploaded on the server etc.

WHM / cPanel (Linux)

cPanel or Web Host Manager (WHM) control panel is a robust tool that provides you with complete management of your Linux hosting account through a single pane of glass.

ZNetLive provides cPanel or WHM control panel with different hosting packages along with several other comprehensive server side services and tools that enable you to manage your account or multiple web sites for multiple clients in case of resellers easily.

In reseller hosting, when you create a new account within your account, a cPanel control panel is automatically assigned to it. You can then manage multiple such cPanel accounts through your own WHM control panel.

Note: VPS and dedicated users have more WHM options as the plans provide root access.

Plesk Onyx

Plesk Onyx is the leading WebOps platform for website owners and web professionals to run, automate, and manage applications and websites with integrated support for Github, Docker, Multi-server management, and ready-to-code framework environment for Node.js, PHP, Python, Ruby on rails, and more. For more details please see Plesk Onyx

WebsitePanel 

The flexible and powerful WebsitePanel platform provides users with simple point-and-click control over Windows Server applications including SharePoint 2010, SQL Server, IIS, Exchange 2010, OCS, Hyper-V Deployments and Lync.

There are multiple advantages of WebsitePanel, including full customization, zero licensing fees, open architecture and complete availability of source code.

WebsitePanel enables one to manage entire hosting environment through a single place, be it deploying servers, creating and managing mailboxes and users, websites and much more.