Hii..All the ex HODs of Allen and bansal are now in nucleus education. In short, the best teachers of Allen are now in nucleus. A healthy and competitive atmosphere is maintained in classroom. Even if Nucleus was formed last year only, these stalwarts have ensured proper discipline, and built upon a competent system for JEE preparation. 

So according to me opting for nucleus will benefit you more that doesn't mean you will get good rank just by joining there you need to put all your effort and revise the topics daily. Prepare well you will make big.

Hope this helps you. All the best.