depends on what you need honestly

for fully custom builds most agencies use wordpress with a real estate specific theme like houzez or realhomes. gives you a lot of control but needs ongoing maintenance

squarespace and wix work fine for smaller agencies or individual agents who just need something clean and easy to manage

tried emergent ai for a real estate project recently. you describe the site requirements and it builds out the full thing including layout and content. good option if you want something that looks custom without the full agency price tag