Nominations accepted and your points are well taken :!:
Just to complete the record, the Elephant would proably have been better off as a tank and not a tank destroyer (OK, it started out as a tank, but didn't make the cut and was revamped as a tank destroyer with a great main gun and armor, but, as you pointed out, no machine gun for close defense).
Also, the Maus was a prototype, not a production vehicle, which was a good thing for the poor wretches who would have had to use it - can you imagine breaking track on something like that

If we went off into prototype land we could come up with some real stinkers
I was lucky enough to be able to tour the 1st Cav Divsion Museum at Fort Hood this past December and they have an M103 on display - what a beast! It made every other armored vehicle there seem tiny - and this included numerous other tanks, trucks, recovery vehicles and SP Howitzers. Haven't been able to see an Elephant in person, but I hear the Ordance Musem at Aberdeen Proving Grounds has one.