I can get a OnePlus 3 (refurbished) in sub 25K from amazon. Is it good step to take though? If not, which smartphone would be the best in the stated budget?
Refurbished phone for 25k is not a great deal considering new one will cost you 3k more my suggestion add 3k more and get OP3 if budget is issue then you can opt for Mi5,Zuk Z2.
Get Oneplus 3 for 28k or wait for Oneplus 3T.
No point in buying a refurbished phone for more than 15k.