• The original developers. Out in the market the longest.
• The free version lacks a lot of features which are included in other VNC clients and it not being actively developed. Not a good thing.

RealVNC provides remote control software which lets you see and interact with desktop applications across any network.

The software has a widespread user base from individuals to the largest multi-national companies. Founded by the original developers of VNC to promote, enhance and commercialise VNC.

TightVNC

• Const Kaplinsky’s project to improve VNC’s compression between server and viewer. Good replacement for RealVNC, but graphic and performance is sluggish sometimes.
• Does not allow remote copy and paste
• The project is being actively maintain, which is a plus.

TightVNC is a free remote control software package. With TightVNC, you can see the desktop of a remote machine and control it with your local mouse and keyboard, just like you would do it sitting in the front of that computer. TightVNC is:

* free for both personal and commercial usage, with full source code available (GPL-licensed);
* useful in remote administration, remote customer support, education, and for many other purposes;
* cross-platform, available for Windows and Unix, compatible with other VNC software.

UltraVNC

• A project to add in file transfer, chat messaging and NTLM authentication to VNC.
• Based on experience, UltraVNC runs faster than the other two and has better graphics.
• Has file transfer, faster connections, chat interface, etc
• Allows you to copy and paste from your local computer to remote computer and vice versa

UltraVNC is a powerful, easy to use and free software that can display the screen of another computer (via internet or network) on your own screen. The program allows you to use your mouse and keyboard to control the other PC remotely. It means that you can work on a remote computer, as if you were sitting in front of it, right from your current location. If you provide computer support, you can quickly access your customer’s computers from anywhere in the world and resolve helpdesk issues remotely! With addons like SingleClick your customers don’t even have to pre-install software or execute complex procedures to get remote helpdesk support.

My recommendation: UltraVNC
So far UltraVNC combines the best of both worlds. Speed, graphic, feature … you name it. It is a clear winner! However, things might be different in 5 years. We shall re-exam again at later time!