[...]H2S is a better baseIncorrect. Think about it again...
I'll try :
H2S vs H2O basicity:
I have to see which lone pore is more ""basic"", more avaiable??
For two different elements of a group the main difference is the size:
S is bigger than O...so O has a bigger electron density...better base?
Now is it correct?
BUT (a big but) if I think at H3O+ vs H3S+ stabilty I can say that H3S+ is more stable because the positive charge is dispersed on a bigger volume...H3S+ is more stable...so H2S is more reactive than H2O in order to form H3S+ (than H3O+ to form H2O)
In other words why is H3S+ less stable than H3O+??
Because this is the requirement in order to have H2O basicity(reactivity towards H3O+ formation ) > H2S basicity(reactivity towards H3S+ formation)