Slayers, Kono Subarashii Sekai ni Shukufuku wo! Recommendations
They are similar in plot devices - the spell system. They both feature idiotic characters to be made fun off.
Their story lines I think are similar. While in Slayers the plot is better developed, in Kono Suba is really not, but they have the same style of plot holes and poor thought story. Comedy in them is very similar aka bad to very bad.
If you really miss Slayers and want to see something similar, I recommend Kono Suba.
Same kind of humor, in a medieval fantasy world with swords and magic.
Comedy adventures shows in a fantasy setting. Neither show ever takes itself too seriously. Both have a cast of four very likable and often incompetent characters.
Both series are comedic fantasy shows about an unorthodox adventuring party getting up to hijinks and parodying others of their ilk.
Both series poke fun at fantasy clichés and feature a delightful cast of oddballs.
While Slayers is not as raunchy as Konosuba, chances are if you like one, you'll probably like the other.