2000 and simcity 5 are the only games that allow online play. From what I've heard 2000's online was amazing and very good however we all know that simcity 5 was a fail and the online in that didn't work correctly. Simcity 4 doesn't have online play but people were able to share cities and download them, many projects were also created to get simcity 4 a online multiplayer but they didn't work.
The sims 1 had a online called the sims online which was also a really good multiplayer game but from what I've heard it costed $15 a month. It got shut down in August 2008 but a new project is currently re making the sims 1's engine and re creating the sims online