There is no "one true answer" as each coin is different, but there is a simple short guideline.

 Coins that have an ASIC option, GPU mining makes zero sense as a GPU can't compete with specialised hardware and will lose money.

 Coins with NO ASIC available and that are GPU mineable it makes sense where the coin can be mined profitably (or at least at close to break if you are hoping for a big pump at some point).

 Coins with no ASIC and no GPU program available, it's not an option.