There are a lot of them but favorite response was written by George Nafziger. The question was "What was the best army in the Napoleonic Wars?" He argued in a very convoluted but convincing way that the Spanish Army from 1808 - 1813 was. His reasoning was that despite all of its problems and although rarely winning a battle, it succeeded in tying up a half million French and their Allies that could have been used elsewhere.
My second favorite topic was fairly recent and called "A Peninsular War Mystery". It lead with the following teasers:
A Portuguese- Spanish- British Light Division Mystery!! Possibly even the Pope is involved!
It is so tough that the first time in 20+ years Ron McGuigan has been stumped!
There are so many possibilities that this could be a mini-series or even a full length movie!"
It had over 371 views, which is a record. It still can be seen at:
http://www.napoleon-series.org/cgi-bin/forum/webbbs_config.pl?md=read;id=188580
And it has never been solved!