When considering a new SNMP monitoring tool try to keep in mind that each basically provides the same functionality and it is first and foremost important to decide what you are trying to accomplish. Meaning what issues are you attempting to resolve by acquiring and deploying an SNMP monitoring tool.
This will help you determine which tool will give you the most bang for the buck.
You should also keep in mind your future needs, if those are currently unknown and you are just entering into this arena then I suggest starting with the most cost effective (cheapest) solution that meets you initial requirements to get your feet wet.
I mention cheapest since you will most likely quickly outgrow the solution and begin looking for a replacement (which is normal) and why you should get your feet wet with an inexpensive solution. Think of this tool as a set of training wheels to get you started and thinking of where you would like to go.
