The temps on the MSI are higher because its a lot quieter due to stock fan speeds, a fact a few reviewers failed to take into consideration.
Also the heatsink is larger, which is a plus point for me with no worries about case room.
You can easily match the Asus for temps by increasing the slow stock fan speed and not be any louder than the Asus.
The backplate is different, but I wouldn't say its any worse for it. certainly doesn't affect temps.
But the Asus is cheaper, so given they are all so similar in performance, that is the bang for buck winner when its priced right.
Not seen any teardowns on the Zotac, but the fact the Zotac has 5 years warranty has to be a confidence booster ?