The most common and some consider traditional way to mic a snare is on the top (batter) head, about 2" off the drum.
Some engineers do like to mic both the top and bottom - the top to get the attack and the bottom to get more of the snare sound.
If you have the mics and channels on the board, use two mics and mix in what you need.
Shure SM57 are by far the most used mic for the top head, (I'v never seen what appears to be clear preference for the snare side), however with the number of new mics on the market, I'm sure there are several people who prefer other mics.