I've found myself in dire need of a web traffic capture tool (specifically for XML debugging). I was using Fiddler on Windows, but I don't know what to use in Ubuntu.
You say "Fiddler" but then link to a "comparison of packet analyzers".
If it is just packet analysis you need, wireshark is the only one I've used, heard, or seen written about. If you need the "man in the middle" packet alteration of Fiddler, I can't advise you.