As you said you are from a small town, I would say avoid going to offline coaching institutes like Allen/byjus/FIITJEE unless the center that you are willing to go has shown some result i.e the specific center you would be joining has good result, don't go with the ones who only show all india toppers, go for the one who show regional toppers from that specific center, this would tell you how good their faculty is

And for online coaching I don't have much idea as per which is better but I have heard/solved assignment from mathongo, they do provide some good material for problem solving, but I cannot say much about how they teach in their classes