"Best" is relative to how you're measuring, and cheapest doesn't mean that's where you want to put all your investment. The cheapest option that can work for some small about of the time can be best by one measurement and not by another.
There are other problems with solar that make it beneficial to offset with other energy sources. For example, lack of ability to generate any energy for 50% of the year, and reduced efficiency depending on weather.
Wind has its own problems as well, but are map to somewhat different circumstances than solar, so is a good supplement for some of the power.
Nuclear has its own problems as well, but unlike wind and solar, many of those aren't inherent to the source, but to how we've developed methods to harness it and deal with produced byproduct (waste). I suspect a first principles approach to nuclear energy might eventually be a very useful source of energy. I think it would be beneficial if we still kept some nuclear around to keep developing it towards a better source. It does well to offset some of the requirements of other systems, which are limited by time, geography or climate.
https://caseyhandmer.wordpress.com/2023/10/19/future-of-ener...