Redfin, but they don't do anything outside of the big cities. (Redfin doesn't service my area, for example - while I used Trulia to look at the school boundary markers and occasionally to look at houses.)
Zillow's site is crap compared to Trulia. Hopefully they acknowledge that and bring Zillow's data onto Trulia's stack.
Ugh, amen! Zillow's interface is horrendous, both from a user and programmatic/scraping standpoint. I've been relying on Trulia for ease of pointing queries at their results pages, so fingers crossed that some of Trulia's sanity trickles into the Zillow site. That article makes it seem doubtful that this will do anything other than beef up Zillow's stack with Trulia's data, though. =/
I've had trouble with Trulia's image serving for the past several months. It seems like their images just take forever to load, to the point that I switched back to Zillow.
Zillow's site is crap compared to Trulia. Hopefully they acknowledge that and bring Zillow's data onto Trulia's stack.