For the Commander ask thing:
I am running a God-Eternal Kefnet deck with the subtitle of "Jank Counterspells". I had to take out my actual Counterspell to fit more bad/value ones like Access Denied and Overwhelming Intellect (the flavour text of which is a personal favourite). The rest of the deck is mostly instant/sorcery value and card draw effects that can trigger on opponent's turns.
Well, I'll start with something pretty obvious, but recent, so might have missed it if you haven't edited it recently.
It's not only a counterspell, it's one that isn't dead if it gets copied by Kefnet in your draw step, AND can have other value either in addition or instead of a counterspell AND an instant speed card draw effect. With that said, it sees heavy play in standard and pioneer, so I don't know if it qualifies under your definition of jank.
While we're on counterspell, another one that'll muck around turns in weird ways. It's not actually all that great because the effects are all very situational (well, other than countering an entire stack) but it's certainly a fun one. Nobody expects the switch of power and toughness.
Generally speaking, modal spells that can be of use whether you're controlling when you draw or not and have a range of applications are your friends.
See Double is a fun card in general, that's almost never dead, and becomes even better in a long game. It's also fun that Kefnet "cheats" its no copying ability; since he copies the card in your hand from where you may then cast it as a spell, it isn't copied as a spell, so the "this spell can't be copied" doesn't apply to Kefnet in specific.
