Type E has the highest sensitivity of typical commercial thermocouples, at ~68 microvolts/K (compared to type J at ~50 microV/K). Agree that types J and K are more common and probably more readily available. Type E is non-magnetic, but not sure if that matters on the OP's application. There are lots of pros/cons to weigh for any temperature measurement - cost, life expectancy, accuracy, ease of measurement are just a few.