I loved Diablo 1 and 2. Never played Diablo 3.
Everybody always said that Grim Dawn would be a true successor and I remember that I completed it but I can't remember anything about that game anymore.
After what they did to Diablo Immortal and WC3:Reforged this does not seem like a company anymore whose products you should be invested in.
Also I can't imagine why you would want to play an open beta. Nowadays you get an open beta at release date and then have to wait ans year until they fixed everything.