No need to rehash the argument from the position preview for centers here, but to quickly recap: For roster purposes, your league should use forwards as all the same position, and if you must separate them, use centers and wingers.
For all the same reasons presented for the centers versus wingers argument, separating players into right wing versus left wing is an even more flawed exercise. The actual roster eligibility in the fantasy game is flawed because the NHL's position labelling system is just as flawed. We are left with labels for players that don't play the position suggested or switch from side to side from shift to shift (while probably taking some shifts at center in between).