From my experience with dragon fruit, the ones in the supermarket or Asian stores are usually really bland most likely due to a lot of them being picked off the plant when they are unripe. I’ve tried a decent amount of dragon fruit fresh off the plant and while some of them were better than others, they all tasted a lot better than the store bought ones. The only one that I would ever get from the stores are the yellow dragon fruit/“ ecuador palora” which are a lot sweeter than the other ones you’d see in a grocery store. Again, it might not be for everyone, but I would highly recommend a least trying a few different cultivars ripe off the plant if possible! I hope this somewhat helped.