Dont really think you can declare a "least dweeby plane." However, I do harbor a degree of E-respect for those who fly unconventional and/or early/mid-war fighters in the LWMA.
Those that come to mind are the 38's, 190A's, 109's and underutilized varients of more popular airplanes such as the 51B, 47D-11/25, etc, etc.
I typically find that those aircraft give the best fights because they are typically driven by players who have been around a while and want a little bit more of a challenge.