Both are the decent college. Acharya Nagarjuna University, Guntur is a Government college & Velagapudi Ramakrishna Siddhartha Engineering College, Vijayawada is a private college. As per the analyzing report of Careers360 Velagapudi Ramakrishna Siddhartha Engineering College, Vijayawada has AAA+ rating which means good. You can check the genuine reviews of the colleges with the given below links.

https://engineering.careers360.com/colleges/acharya-nagarjuna-university-guntur

https://engineering.careers360.com/colleges/velagapudi-ramakrishna-siddhartha-engineering-college-vijayawada

Good Luck!