In electroconvulsive therapy (ECT), the use of anesthetics without relevant anticonvulsant properties such as ketamine and etomidate may be favorable for seizure quality. Since there is a relative paucity of studies devoted to this issue, our aim was to compare different anesthetics for ECT regarding their impact on seizure quality and different seizure parameters. We retrospectively compared ketamine (n = 912 anesthesias), etomidate (n = 227 anesthesias), thiopental (n = 2,751 anesthesias), and propofol (n = 42 anesthesias) on their influence on general seizure quality and different seizure parameters by multivariate repeated measurement regression analyses. The use of ketamine and etomidate as anesthetics led to seizures that were overall higher in quality and also longer in motor seizure activity when compared to anesthesia with thiopental and propofol. Ketamine was most favorable concerning central inhibitory potential that was indirectly quantified by concordance and postictal suppression. The worst seizure quality was observed with propofol anesthesia; further, this substance had a negative impact on autonomic activation and seizure duration. Based on the data of this retrospective study, the use of ketamine or etomidate as anesthetic in ECT might be advantageous due to the induction of high-quality seizures.