没有最差, 只有更差
choose your desired location, then check with TARION or BBB for the builders who are building in that area. Go around neighborhood built with that builder and ask home owners' opinion for that builder. etc. etc.
Heard that cardel, monark and some small builders are better than others. But no matter you go with anyone, you always need to be prepared to deal with the worst case. IMHO.