My recommendation: BIGTREA PREMIUM. Recently ordered, it is pretty good quality. Give it a try. They also have lab test available for all the batches, and you can choose from 3 strength. Not the cheapest, but at least good quality.

The bigtrea Premium Kratom 1.3-1.7% mitragynine is great like you say but do you have experience with the bigtrea XRELEAF 10% or 20% mitragynine extract? In the past I had only bad extracts, no matter from which vendor but I heard many people saying that is the first good extract. But really not sure if they know what they are talking about, is it worth trying?