The biggest Hydro plant in the US is the Grand Coulee dam in Washington, with a nameplate capacity of 6,809MW. This is pretty impressive, but it's a heck of a lot more than most hydro plants could ever hope to produce. Only one other dam beats out 3,000MW, barely, and most are in the ~2,500 MW range. Overall America has 79GW[1] worth of hydro power capacity.
Now ~2,500MW per dam is a lot, but it's actually kind of low compared to nuclear power. America's newest operating power plant, Watts Bar, has a nameplate capacity of 2332MW, which would put it at number 6 in the hydro plants list. And Watts Bar is fairly small compared to most other nuclear power stations around, since it only has two reactors. 6-7GW nuclear power plants are far from unheard of[2], and most of the older French reactors hang out in the 3GW range.
In places where hydro fits the geography, it's a great choice. Not without its tradeoffs, but miles better than coal or natural gas. But overall nuclear is still going to beat the pants out of it for versatility, and total generation capacity.
0 - To be fair, this can be a benefit in cases where you need to both generate electricity and store water for later use.
1 - Peak production. Yearly energy measured will be higher, roughly 270TWh, because there are a lot of hours in the year. Still a heck of a lot less than the ~800TWh of nuclear power we were making per year last year.
2 - Japan, China, and South Korea run a total of 5 nuclear plants with >6GW capacity. Japan and South Korea each have a plant with >7GW capacity. South Korea, Ukraine, China, and France run a combined seven reactors with a capacity between 5 and 6GW. The French reactors are interesting because they're all pretty old, from the 1980s, and were built and commissioned on a tight schedule, with an average construction time of 7 years.
