Oddest: Run Lola Run, a German language film, has a commentary by the German director and German star in English. Nice, but very unexpected.
“The City of Lost Children”, a French film, is done sort of the same way. The director, Jean-Pierre Jeunet, is French but speaks English for the commentary. The other guy on the commentary is Ron Perlman, American.
Best: Roger Ebert on Dark City (this put a movie in context better than most any other commentary), Steven Soderbergh and screenwriter Lem Dobbs on The Limey (this put the script to screen conflict into context better than most any other commentary), and Kurt Russell and John Carpenter on Bit Trouble in Little China (this one was mentioned as a worst, but I liked it because I came away with a great sense of these two as people and how they approach movies).
Worst: Roger Ebert on Citizan Kane (I know it has several mentions of best, but it was obviously done in segments and repeated itself terribly; it isn’t bad, but I give it worst since it should have been so much better). Beyond that there are many worst from me, if it isn’t good I usually just stop listening right away.