I my opinion you should still mine but have more diversity in what you are mining but with the majority of it in your preferred cryptocurrency and the remaining to other altcoins. Also if you think that you already have used the GPUs to a certain extent then it is time for you to sell it and buy a new one though buying a new set of GPU might be a waste of money since the market is in a bearish state. Well in the end it is up to your choice.

if you don't need urgent money and you've covered your costs as roi suggest you mining low-volume coins on the market. Suqa as a good start can be for you