Hydro is good when it’s available but also has some significant problems. The biggest is that it’s an ecological disaster even if the reach of that disaster is far more limited. The areas upstream of the dam flood while the ones downstream are in constant danger of flooding and drought. In the worst case if the dam collapses it can wipe entire towns off the map with little or no warning. It is objectively far more dangerous and damaging to the environment than any nuclear reactor. The only upside it has is that it’s effectively infinitely renewable barring massive shifts in weather patterns or geology.

All of that is of course assuming that hydro is even an option. There’s a very specific set of geological and weather features that must be present, so the locations you can power with hydro power without significant transport problems are limited.

It’s certainly an option, and better than coal, oil, or gas, but still generally worse than nuclear.