I have previously used Wireshark. One of the differences between OmniPeek and Wireshark is in the test bed OmniPeek allows you to choose a color coding for each and every component. You can set the color of many components, such as the client based on your interest, and MAC address. You are able to see certain packets from the APs easier. Wireshark is more user-friendly for automation and OmniPeek is good for manual testing.

Wireshark cannot be run continuously because the buffers will be used up after half an hour and the application crash. However, in OmniPeek this does not happen it continuously starts until the memory space is consumed. It will not crash. You can run it for twelve hours continuously and it will save without crashing.

I have three years of prior experience using Wireshark. We have gotten higher performance with OmniPeek. 

I use Wireshark, which is a free, open-source package. I am still using both of them because of how the two products represent information. OmniPeek is a superior product, but I correlate the information from Wireshark because sometimes it gives me a quicker indication of what I am looking at.