A few comments:
1) 2014 will be the third year of the production run, not the second year. The 2013 is a second year production car and it is solid. The US was the only country not to sell 2012 M5s, in EMEA, Canada and Asia the 2012 M5 was sold in large numbers.
2) The LCI will not be a huge departure. The biggest upgrade was the iDrive upgrade and we already got that in 2013. The changes are only cosmetic - no new features/tech (with exception of LED lights). BTW the new tail lights look very similar to the current ones. I often can't tell the difference between an F30 and an F10 when approaching from behind. And I think the non LED headlights look better because of the round Halos.
3) If you are buying, resale takes a dip everytime the model year changes. I would not buy a new car in March/April. It just doesn't make sense economically. You are best off buying in September at the start of the model year (July/August production cars). This said, if you are leasing it is irrelevant.
My advice - if you can find a suitable 2013 on a lot do it now. You will have longer to enjoy the car. If you must order one, I would still get a 2013 if you are leasing but wait for a 2014 if you are buying.
2014 Porsche 911 Turbo S
2015 Mercedes-Benz C300 Sport 4MATIC