I feel you, some strains (usually malaysian varietals) give me pure anxiety and no euphoria. It's almost like there is some threshold where anxiety overrides any pleasure from certain strains. That's just the nature of the kratom game, sometimes you win sometimes you lose as far as quality goes. I reccommend searching for a vendor that displays alkaloid content so there's less gamble. Usually you can find vendors that display mitragynine content.
On the topic of "grainy kratom", that's just the way it was ground and not the best indicator of potency. Most vendors will micronize their kratom to the point it becomes a clumpy, fresh, flour like consistency, this is probably what your used to. Every once in a while I get a poorly grinded strain that I assume is what your referring to when you talk about grainy kratom.
Here's a pic of three strains, the grainy stuff is from a different vendor than the others. From left to right here's a tsp each of red vein borneo, super indo, and bali. Despite not being micronized like the other two, the first is plenty potent, though it does fall short compared to the others. Because this photo was taken at night it's hard to get a shot that captures the true color of the strains, but the middle strain is a nice blonde while the bali is almost a lime green and the RVB is a tad bit lighter.
