See, as you are from Delhi only and took coaching previously, so you already know the cultures in both fiitjee and vmc.
Fiitjee doesn't give much attention to the lower batches, but as you already mentioned there are doubt clearing classes, you can anyways go there.
Now, coming to your current situation.
As you mentioned you don't have much doubts in Chem and Maths, and Chem is the subject that has problem with most of the droppers as its highly scoring and people can't perform upto their potential, but I think, that's not the case with you.
So, fiitjee will be a better option I guess.
But still, I would suggest you not to just rush into anything, wait for results for the results so that we can think which batch will you get , and keep us updated.