The San Francisco League of Pissed Off Voters has things to say about London Breed (http://www.theleaguesf.org/#london) and Jeff Sheehy (same page, scroll down).
There will always be organizations out there criticizing any candidate, but at the end of the day, Jane Kim doesn't believe the laws of supply and demand apply to San Francisco housing[1][2], while London Breed is the only candidate who supported SB-827[3].
