Why use Whatsup Gold Instead of PRTG?

I been looking for a application to use for my monitoring in my server, I very tired of monitoring manually so i decided to search some of the best monitoring application, not its quality only but also the price that I can afford as well. When I was searching online I discovered or I see this two (2) software, What application I mean is the PRTG and the WHATSUP GOLD. But I wonder if which of this two (2) application is good and nice to work with. Other say's that PRTG is good, but other say's the WHATSUP GOLD. But this two (2) kinds of application is totally need a lot of bucks. I just wanna ask If you know or have an application that is free to use. I'm still searching for some documentation of this kind of application. And I also wrote this article to some reaction, and some suggestions. Before that I wanna share this PDF article that I found online I just wanna hear your side guy's about this, if this is true.

Now lets discovered the features of this application

PRTG Network Monitoring Features

• Quick Download, Installation and Configuration
• Easy to Use: Choose Between Five User Interfaces
• Comprehensive Network Monitoring
• Flexible Alerting
• PRTG Cluster Failover Solution
• Distributed Monitoring Using Remote Probes
• Data Publishing and Maps
• Easy to Understand - Multi Language Interface
• High Performance Design and High Security Standards
• In-Depth Reporting
• Support for Customization

WHATSUP GOLD Features

Visit Some Forum : Reason why no use PRTG