Suburbia is the better of the 2 games. I played The Great Fire of London 2 years ago and didn't care much for it, other than the history of it which can be interesting to anyone who doesn't have prior knowledge. My only complaint about Suburbia is that there's goofy/negative goals (worst reputation, least income, etc.) that come into play that seem a bit dubious to me. My opinion on that though is no doubt influenced by also being a wargamer.
Interesting enough, Suburbia reminded me of another very good tile placement game I own called Vikings. I only mention it because IMO the screw you factor in Vikings is better as long as you play it with the advanced auction rules.