The chocolate cake/frosting on the Hershey chocolate powder box is the best and easiest cake ever
I also make a blitz-kuchen which is good - you can rev it up with lemon, orange or almond or just leave it as a simple vanilla cake - as they say in the German neighborhoods in Brazil, cafe und kuchen
I like red velvet cake but I am a snob about it and only like the original recipe from I think the Ritz in NY and not grocery store cake - the story goes the baker was let go and as revenge, he published the well guarded secret recipe for his red velvet cake in the NY Times - that's the best recipe ever - it is more involved with the whole folding in thing, but it is worth the effort to do it right
one bowl cake recipes are so easy and great so you never need a box mix, just don't do it
...and additionally, the best cake euphuism was done by none other than the B-52's - it's one of my favorite songs of theirs -