It will sound like an advertisement but it's not. I've recently tested the ''revamped'' substance Library and there are a ton of good materials in there.
Guys, for 19,99$/month you get all Allegorithmic's Tools + access to the Library here https://source.allegorithmic.com/#/substances/home

While we wait for quixel to release megascans architecture materials, it's a very good alternative.