On a yield basis the cheapest to short is EQB (borrow is very cheap). I am short that too.
I hear you on MIC, however with increased capital requirements don't be surprised if the div gets cut. If it doesn't get cut for that reason you may only have to pay for a year or more until the losses force them to cut to 0.
If you are institutional shorting the corp bonds is the cheapest way to play this (if you know a platform that retail can do that please let me know). Otherwise I just short the stock, puts are too short dated for my liking.