Please help me decide which Air India business class flight should I book

I have a few travel plans this spring(domestic and international) and I will be traveling from Delhi in business class. I have read many people complaining about old and non functioning business class being offered to them. Is there any way to see which business class would be offered while booking, also can anyone suggest me which Air India have new and refurbished business class configuration including vistara.

Ps:- I just know that flight number starting with 2 are vistara aircraft and these air craft have good business class :-A350, Delta and Etihad 777,Vistara 787 and A321 neo.

What all aircraft in air india have good business class configuration?