Nuclear. Naive probability matters relatively little here. The risk of coal plants due to CO2 is a thin-tailed long term risk. No single coal plant will ever cause a headline (or an event) like this. Thin-tailed long-term risks can be mitigated and planned for and the result is always a sum of many smaller choices (albeit global warming is an existential risk for sure!).
Nuclear is different. 99,999% of time it's cheaper and cleaner than coal. Doesn't matter. The tail-risk is what matters and that's also, why (conventional) nuclear can't ever be economically competitive against any other power source without direct or indirect subsidies (there is no insurance that will insure a nuclear power plant).
Highly recommend Taleb`s paper on fat-tailedness [1].