If you want to get a isolating earphone, E3C will be the best choice, slightly costly at a price of 200-299 with better base sound then E2C and E500 with 3 drivers are not really recommended unless you have god ears for listening to drums(as many musicians only uses E3C) and even top models in ear monitor from Shure uses E3C the most.
Another thing to take note:
E2C is going to discontinued. There are new models from Shure, the SE series are coming out, I reommend SE310 for your drums. Any informations about microphones, headphones and professional recordings, you can always pm me.