So far I have only tried Inawera Watermelon and Caramel and there both good at lower percentages. At 3% the INW watermelon tastes real, good flavor and was one of my favorites, just edged out by FA, Cap and TFA but was probably the most authentic flavor, just don't go over 3% as it gets worse. The INW caramel at 1% was my favorite over FA, Cap, TFA, Hangsen and Lorann.
I have only tried Hangsen Caramel but it was good at 3%. I have 4 other Hangsen flavors, 3 coffee types and 1 cream and they all smell good but about as potent as the caramel so there probably in the 3% range.
So far my experience with Inawera is it is really concentrated so a little goes a long way, keep in mind that is only with 2 flavors though. I also have INW Two Apples and just just gave it a smell, smells strong and delicious so I am guessing it is also a low percentage flavor, my guess would be around 1% as it smells just as strong as FA Fuji Apple.
This was all standalone tests I did on these flavors, in a mix it can all be different depending on which flavors your using.