It depends on if you can accept the fluid to leak. Generally speaking, The seal type is seal designed on the top to prevent the leakage. It can be used with the higher temperature or corrosive, noble fluid. The lever type have the manual discharge testing function so it’s not 100% sealed. It can be use with water, and other fluid that’s safe to be leaked. Also, due to the complexity of the structure. The price of the lever type is higher than the seal type.