I'm a fan of "wear what you want". I do think wearing an entire team kit does look a bit w*nky but each to their own. I don't judge those that do, coz I'm just happy to see them out riding - the more the merrier.
Regarding showing off sponsors, well, it supports those who support us, and that should be done no matter how you do it.
Commuting, I wear whatever's visible and comfortable.
For longer weekend or other rides, I generally ride in a shop kit of my LBS, however, now that I'm in a different country there isn't a huge point in it as a way of supporting that store that's not here...
I do have a saxo l/s jersey that I use in winter, an old wool Lotto-Tonisiter, a Jamis jersey (only if I ride my Jamis) and a few hometown UniSA jerseys that all get some use.