After the merge, there won’t be a dominant coin to mine. Maybe a few months afterward? However, during the aftermath, we probably will see a Darwinian competition for dominance but will take some time. Though it will probably look more like Brownian movement (good time for a quantum computer)
Also depending on what you want (coins or cash), you will have to decide on something like an auto-switching scheme that gives you the most cash or hodling. If hodling the coins regardless of the current profitability, until the coin appreciates (unless it goes to the moon like luna), you will need to research the coin
As Keaton said no one knows, even months post-merge. The dust will probably take a while to settle. Doubt any coin has the capacity or tokenomics to deal with the tsunami of miners that are coming. It will be interesting times and very dynamic. Many coins will do the way of the dodo, so choose wisely.
Another option is to shut down until things settle, especially if you can’t meet your mining costs