Definitely each brand, and actually each individual flavor, is different in regards to the percentage you need to use. The key is knowing the flavor and how it tastes at different percentages in different mixes.
I suggest to start by picking a flavor you like and want to mix . .and then research here to see which brands of that flavor are popular . .and then mix a batch with that single flavor at a low percentage, make enough that you can try some right away and then try it again a week later . .and then go from there.
I started with Lorann's but switched to TFA. I like Loranns, definitely, but more people use TFA so I can find more information and recipes . .and the TFA flavors, for the most part, seem to require me to use less than Lorann's . .which is a bonus, as well.
I am a low flavor vapor .. but I tend to start with 3% for most flavors and usually settle on no more than 6% of any one flavor in a mix. I started out mixing 20% . . .did not care for those juices at all and was very discouraged until I dropped the flavor percentage down dramatically.