You can always just get a range strengths, smaller bottles of
juice are relatively cheap, I have been experimenting with higher and lower strength juices. I
vape in the 6-8mg range still mainly, but probably because I chain vape a lot right now. It's new to me, and there are tons of things to try, I have a couple 12,18 and 24mg juices now too. I do find them good when I go out for a quick break and need some nicotine in a hurry that will last til the next one.
Best you can do is experiment and find what is right for you. None of us can really tell you that, and I agree the smoked X should vape X is not all that true for a lot of people.
Also, if you have not already... read this post:
Understanding your symptoms while adjusting to vaping. as well as
List of symptoms when quitting tobacco...