This is only a partial answer since you have left many questions unanswered.
But a) many juice makers will sell sample packs of low mg to try some different flavors. And if you are lucky enough to have a Brick and Mortar with a Sample bar head over there to find out the types of juice you like.
I can't speak to nic levels and PG/VG ratios as it's hard to say.
I am PG sensitive and no more than 10% works (I save it for my flavorings) without a horrible, burning pins and needles feeling in my throat.
Please note I am NOT saying you are PG sensitive it could be a jillion other things, so fill us in so we can help you better.
Anna