Generally, I prefer fics that take the most recent canon into account, but it depends a lot on what specific changes are made and who the fic centers on. I could read a recent fic where Sirius was alive if he was a minor character; not so much if it's a Sirius/Remus fic, for example. I also tend to prefer it if there's a reason besides "I want it to be this way." We know in canon now that there is no Snape Manor, but if your premise is that Snape is from an old wizarding family and Lucius recruited him as a DE for that reason, that's one thing. If you make Blaise Zabini white because you can't deal with the fact that canon!Blaise is black, that's another issue entirely.