They should be red/orange in color and should leave a fingerprint when touched.

it depends which type of persimmon you have. If you have hachiya, which are sort of longer, then they are not ripe until pretty mushy. If you bite into an underripe hachiya (and they take forever to ripen) you will have that horrible dryness in your mouth for a while. Fuyu persimmons, on the other hand, are more tomato shaped and can be eaten while still hard. I like fuyus a little softer than that, but not mushy. I only buy fuyus now, If you search "persimmon" here on food pickle you'll find a couple of earlier threads that might include photos.

i usually try this too, however last time I bought them I used this rule and they were super dry and full of tannins.

My rule of thumb for all fruit is to smell. If they smell sweet, even faintly, they are ready to go. Also, if they give a little, that's a good sign. Not rock hard, not squishy. Somewhere in between. I know this might not be super helpful or specific, but I trust my instincts more than any hard & fast rules!